Detailed explanation of permission management in mysql learning

The meaning of database permissions:

In order to ensure that the business data in the database is not illegally stolen by unauthorized users, various restrictions need to be imposed on the visitors to the database, and DatabaseSecurity There are three main types of security control measures. The first is user identity authentication, which can be password, magnetic card, fingerprint and other technologies. Only people with legal identities can enter the database. The second type of access permission control. Different roles have different access permissions to the database. The database object and permissions they access must be set for each role. The third type is to formulate a management system for database management. The system ultimately restrictspeople'sbehavior. By formulating corresponding rules and regulations, it can ensure that the data is processed by the right people at the right time. Proper operation.

mysqlThe check of user permissions is divided into two stages

1. Whether a link can be established with the mysql server

2. Whether there are certain Operation permissions (such as: select update, etc.)

1. Establish a link with the mysql server

How does the mysql server verify whether the user can establish Link

1. Verify where you come from host

2. Who are you user

3. Password password

How to link to mysql: C:\Users\PC003>mysql -h192.168.6.223 -uroot -pjalja

Parameter explanation: -h: Where to establish the link

　　-u： user

　　 -p：Password

mysql> select user,host,password from user;
+------+-----------+-------------------------------------------+
| user | host      | password                                  |
+------+-----------+-------------------------------------------+
| root | localhost | *CFAFE434FB0E5D64538901E668E1EACD077A54DF |
| root | %         | *CFAFE434FB0E5D64538901E668E1EACD077A54DF |
+------+-----------+-------------------------------------------+

host=localhost indicates that the default host can be used for linking (C:\Users\PC003>mysql -uroot -pjalja, C:\Users\PC003>mysql -hlocalhost -uroot -pjalja, C:\Users\PC003>mysql -h127.0.0.1 -uroot -pjalja)

host=% means that the server can be connected to the same local area network (public network) where it is located ). This method is not safe in a production environment.

host=192.168.6.224 means that the server can only establish links with the 192.168.6.224 host C:\Users\PC003>mysql -h192. 168.6.223 -uroot -pjalja

How to modify host:

mysql> update user set host='192.168.6.223' where user ='root'

mysql> flush privileges; refresh permissions (because the modified data is in memory each time the user operates Permission-related operations must be refreshed)

Change password:

mysql> update user set password=password('111111') where user='root';
mysql> flush privileges;

2. How to check permissions in mysql

mysql There is a mysql library in the library. The user table under the library checks whether the user exists, the db table checks what operating permissions the user has on which libraries, and the tables_priv table checks what operating permissions the user has on those tables.

Create user and authorize:

grant [Permission 1, Permission 2] on *.* to user@'host' identfied by 'password';

Common permissions: all, create, drop, insert, delete, update, select

For example: grant the ls user all permissions to all databases and all tables and can log in from any host in this LAN segment.

mysql> grant all on *.* to 'ls'@'192.168.6.%' identified by '111111';

Use this user to log in: C:\Users\PC003>mysql -h192.168.6.223 -uls -p111111;

View the specific permissions of the ls user:

mysql> select * from  mysql.user where user='ls' \G;
*************************** 1. row ***************************
                  Host: 192.168.6.%
                  User: ls
              Password: *FD571203974BA9AFE270FE62151AE967ECA5E0AA
           Select_priv: Y
           Insert_priv: Y
           Update_priv: Y
           Delete_priv: Y
           Create_priv: Y
             Drop_priv: Y
           Reload_priv: Y
         Shutdown_priv: Y
          Process_priv: Y
             File_priv: Y
            Grant_priv: N
       References_priv: Y
            Index_priv: Y
            Alter_priv: Y
          Show_db_priv: Y
            Super_priv: Y
 Create_tmp_table_priv: Y
      Lock_tables_priv: Y
          Execute_priv: Y
       Repl_slave_priv: Y
      Repl_client_priv: Y
      Create_view_priv: Y
        Show_view_priv: Y
   Create_routine_priv: Y
    Alter_routine_priv: Y
      Create_user_priv: Y
            Event_priv: Y
          Trigger_priv: Y
Create_tablespace_priv: Y
              ssl_type:
            ssl_cipher:
           x509_issuer:
          x509_subject:
         max_questions: 0
           max_updates: 0
       max_connections: 0
  max_user_connections: 0
                plugin:
 authentication_string: NULL

Permission recovery: revoke all permissions of ls

mysql> revoke all on *.* from ls@'192.168.6.%';

Authorize someone Library permissions:

mysql> grant all on blog.* to ls@'192.168.6.%'; Grant the ls user all permissions to the blog database.

In this way, the ls user has no permissions in the user table. At this time, a db-level permission check will be performed.

mysql> select * from  mysql.db where user='ls'
\G;*************************** 1. row ***************************
                 Host: 192.168.6.%
                   Db: blog
                   User: ls
          Select_priv: Y
          Insert_priv: Y
          Update_priv: Y
          Delete_priv: Y
          Create_priv: Y
            Drop_priv: Y
           Grant_priv: N
      References_priv: Y
           Index_priv: Y
           Alter_priv: Y
Create_tmp_table_priv: Y
     Lock_tables_priv: Y
     Create_view_priv: Y
       Show_view_priv: Y
  Create_routine_priv: Y
   Alter_routine_priv: Y
         Execute_priv: Y
           Event_priv: Y
         Trigger_priv: Y

Recover all permissions of the ls user and grant permissions to a certain table: Grant the ls user crud permissions of the user table in the blog library

mysql> revoke all on *.* from ls@'192.168.6.%';
Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql> grant insert,update,select,delete on blog.user to ls@'192.168.6.%';
Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

In this way, the ls user does not have permissions at the db level. At this time, the permissions check at the tables_priv level will be performed:

mysql> select * from  mysql.tables_priv where user='ls'
\G;*************************** 1. row ***************************
       Host: 192.168.6.%
         Db: blog
         User: ls
 Table_name: user
    Grantor: root@localhost
  Timestamp: 2017-02-09 14:35:38
 Table_priv: Select,Insert,Update,DeleteColumn_priv:1 row in set (0.00 sec)

mysql permission control Process:

#Note: MySQL's permission check can be accurate to a certain column of data.

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