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This article will explain in detail the example analysis of MySQL users and permissions and cracking root passwords. The editor thinks it is very practical, so I share it with you for reference. I hope you can get something after reading this article.

MySQL users and permissions

In MySQL, there is a system with its own database called MySQL. After the database is installed, the system comes with several databases MySQL is one of them. MySQL database has a table related to user account permissions called user table, in which there are created users.

The full user name in MySQL is formed by the user + host name, which determines the host on which the user can log in.

I. user creation and password modification

1. The creation of users

Create user 'USERNAME'@'HOST' identified by' PASSWORD'

USERNAME: user name

HOST: host addr

PASSWORD: password

Example:

MariaDB [(none)] > create user masuri@192.168.73.133 identified by 'centos';Query OK, 0 rows affected (0.01sec) MariaDB [(none)] > select user,host,password from mysql.user +-+ | user | host | password | +-+- -- +-- + | root | localhost | root | localhost.localdomain | root | 127.0.0.1 | root |: 1 | localhost | localhost.localdomain | | | masuri | 192.168.73.133 | * 128977E278358FF80A246B5046F51043A2B1FCED | +-+ 7 rows in set (0.00 sec) |

There are anonymous accounts in MySQL, which can be deleted by running the security hardening script mysql_secure_installation or manually.

Delete a user:

DROP USER 'USERNAME'@'HOST'

Example:

MariaDB [(none)] > select user,host,password from mysql.user +-+ | user | host | password | +-+- -- +-- + | root | localhost | root | localhost.localdomain | root | 127.0.0.1 | root |: 1 | localhost | localhost.localdomain | | | masuri | 192.168.73.133 | * 128977E278358FF80A246B5046F51043A2B1FCED | +-+-- +-+ 7 rows in set (0.00 sec) MariaDB [(none)] > DROP USER'@ 'localhost' | Query OK, 0 rows affected (0.00 sec) MariaDB [(none)] > DROP USER'@ 'localhost.localdomain';Query OK, 0 rows affected (0.00 sec) MariaDB [(none)] > select user,host,password from mysql.user +-+ | user | host | password | +-+- -- +-- + | root | localhost | root | localhost.localdomain | root | 127.0.0.1 | | root |:: 1 | | masuri | 192.168.73.133 | * 128977E278358FF80A246B5046F51043A2B1FCED | +- -- +-+ 5 rows in set (0.00 sec)

two。 Change of password

Modification of mysql password

SET PASSWORD FOR user = PASSWORD ('cleartext password') UPDATE table SET password = password (' cleartext password')

Example:

Change the password for masuri users

MariaDB [(none)] > SET PASSWORD FOR masuri@192.168.73.133 = PASSWORD ('magedu'); Query OK, 0 rows affected (0.00 sec) MariaDB [(none)] > select user,host,password from mysql.user +-+ | user | host | password | +-+- -- +-- + | root | localhost | root | localhost.localdomain | root | 127.0.0.1 | | root |:: 1 | | masuri | 192.168.73.133 | * 6B8CCC83799A26CD19D7AD9AEEADBCD30D8A8664 | +- -the password has changed at this time

The password for the root account is empty. Set the password for the root password. Because the setting of one entry is too troublesome, you can also use the operation of modifying the table to change the password.

MariaDB [(none)] > update mysql.user set password=password ('centos') where user='root';Query OK, 4 rows affected (0.01sec) Rows matched: 4 Changed: 4 Warnings: 0MariaDB [(none)] > select user,host,password from mysql.user +-+ | user | host | password | +-+- -- +-+ | root | localhost | * 128977E278358FF80A246B5046F51043A2B1FCED | | root | localhost.localdomain | * 128977E278358FF80A246B5046F51043A2B1FCED | | root | 127.0.0.1 | * 128977E278358FF80A246B5046F51043A2B1FCED | | root |:: 1 | * 128977E278358FF80A246B5046F51043A2B1FCED | | masuri | 192.168.73.133 | * 6B8CCC83799A26CD19D7AD9AEEADBCD30D8A8664 | +-+- -+-+ 5 rows in set (0.00 sec)

At this time, the password has been changed but still cannot be logged in. You need to refresh the permissions.

MariaDB [(none)] > FLUSH PRIVILEGES;Query OK, 0 rows affected (0.00 sec)

II. MySQL authority management

Rights management involves a variety of categories of permissions, such as administrative classes, program classes, database levels, table levels, and field levels.

Management class: can you create users, display database lists, reload configuration files, close databases, manage processes related to replication, create temporary tables, and create files in the database?

Program classes mainly involve three programs, functions, stored procedures and triggers, such as whether you can create, modify, delete and execute these libraries, table and field-level permissions: for example, whether you can add, delete, query, change and other operations in the library and table fields.

1. Authorized GRANT

When authorizing a user, if the user does not exist, you can create it. Before authorizing the user, you must first make sure that you are an administrator with authorized rights.

GRANT priv_type [(column_list)] [, priv_type [(column_list)]]... ON [object_type] priv_level TO user_specification [, user_specification]... [REQUIRE {NONE | ssl_option [[AND] ssl_option]...}] [WITH with_option...]

Example:

Create a wordpress user and authorize it.

MariaDB [(none)] > CREATE DATABASE wordpress;Query OK, 1 row affected (0.02 sec) MariaDB [(none)] > GRANT ALL ON wordpress.* TO wpuser@'192.168.73.%' identified by 'mylinuxops';Query OK, 0 rows affected (0.00 sec)

two。 View the user's permissions

MariaDB [(none)] > show grants for wpuser@'192.168.73.%' +-+ | Grants for wpuser@ 192.168.73.% | +- -+ | GRANT USAGE ON *. * TO 'wpuser'@'192.168.73.%' IDENTIFIED BY PASSWORD' * EC0DBFB480593BB6ED2EC028A4231A72D8137406' | | GRANT ALL PRIVILEGES ON `wordpress`. * TO 'wpuser'@'192.168.73.%' | +-- -+ 2 rows in set (0.00 sec)

3. Other options for authorization

MAX_QUESRIES_PER_HOUR count # maximum number of times per hour MAX_UPDATES_PER_HOUR count # maximum number of changes per hour MAX_CONNECTIONS_PER_HOUR count # maximum number of connections per hour for MAX_USER_CONNECTIONS count # users

Revoke the right

REVOKE priv_type [(column_list)] [, priv_type [(column_list)]]... ON [object_type] priv_level FROM user [, user]...

Example:

MariaDB [(none)] > revoke delete on wordpress.* from wpuser@'192.168.73.%';Query OK, 0 rows affected (0.00 sec) MariaDB [(none)] > show grants for wpuser@'192.168.73.%' +- -+ | Grants for wpuser@192. 168.73.% | +- - -- + | GRANT USAGE ON *. * TO 'wpuser'@'192.168.73.%' IDENTIFIED BY PASSWORD' * EC0DBFB480593BB6ED2EC028A4231A72D8137406' | | GRANT SELECT INSERT, UPDATE, CREATE, DROP, REFERENCES, INDEX, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, EVENT TRIGGER ON `wordpress`. * TO 'wpuser'@'192.168.73.%' | +- - -+ 2 rows in set (0.00 sec) # wpuser@'192.168.73.%' no longer has delete permission

Cracking the root password of MySQL

You may sometimes encounter the loss of root password at work, and you can retrieve the root password in the following ways

Here is a demonstration of how to crack the root password

1. Unable to log in to MySQL with unknown password

[root@localhost ~] # mysqlERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)

Second, crack

1. Modify the configuration file / etc/my.cnf to add two lines of parameters

Skip_grant_tables: skip the authorization form information. After this item takes effect, you don't need to use a password to use MySQL again, but other remote users can log in without a password, which is risky.

Skip_networking: turn off the network function. Because only the skip_grant_tables option is enabled, other users can also log in to MySQL without a password. It is very dangerous, so it is necessary to turn off the network function and only allow local users to operate.

[root@localhost ~] # vim / etc/ my.cnf [mysqld] skip_networking=on # does not enable network features skip_grant_tables=on # Skip authorization table [root@localhost ~] # service mysqld restart # restart the service Restarting mysqld (via systemctl): [OK] after modifying the location file

two。 Log in to MySQL and change your password

[root@localhost ~] # mysql # can now log in to Welcome to the MariaDB monitor without entering a password. Commands end with; or\ g.Your MariaDB connection id is 11Server version: 10.2.23-MariaDB-log Source distributionCopyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or'\ h' for help. Type'\ c'to clear the current input statement.MariaDB [(none)] > UPDATE mysql.user SET password=PASSWORD ('123456') where user='root'; # modify the password of root Query OK, 4 rows affected (0.01 sec) Rows matched: 4 Changed: 4 Warnings: 0

3. After the password has been modified, the configuration file needs to be restored

Log out or delete the two options you just enabled, and then restart the service

[root@localhost ~] # vim / etc/my.cnf [mysqld] # skip_networking=on # skip_grant_tables=on [root@localhost ~] # service mysqld restartRestarting mysqld (via systemctl): [OK]

4. Log in to MySQL with a new password

[root@localhost] # mysql-uroot-p123456 Welcome to the MariaDB monitor. Commands end with; or\ g.Your MariaDB connection id is 10Server version: 10.2.23-MariaDB-log Source distributionCopyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.Type 'help;' or'\ h' for help.

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