MySQL系列(十)--用户权限及远程访问

　　本文基于MySQL8.0，记录一下完整的远程访问的过程，以及这个过程中可能遇到的问题，MySQL运行在阿里云服务器，操作系统：CentOS 7.6 64位

顺便说下，买服务器还是要双十二这种拉新活动再买，用一个新的支付宝账号购买，能便宜一大半，不然双核4G就两千多块了。

　　这里默认防火墙已经向外暴露3306端口/关闭防火墙了，以及阿里云安全组配置暴露3306端口，在Windows通过Navicat测试连接

随便创建一个用户：

mysql> create user 'dev'@'localhost' identified by 'huluhulu';　　//创建用户dev，只能在localhost使用，密码huluhulu
Query OK, 0 rows affected (0.00 sec)

mysql> select host, user ,authentication_string, plugin from user;　　//查看user，host，加密后的字符串，以及加密类型
+-----------+------------------+------------------------------------------------------------------------+-----------------------+
| host      | user             | authentication_string                                                  | plugin                |
+-----------+------------------+------------------------------------------------------------------------+-----------------------+
| %         | root             | *43C685FF9E03403DD721CF54B4E40B199DA06624                              | mysql_native_password |
| %         | test             | *43C685FF9E03403DD721CF54B4E40B199DA06624                              | mysql_native_password |
| localhost | dev              | $A$005$6dH-H    a.'^JNmbBkSYomGJK2180WHglWpm4mw.BIJGtuPX0qcBrOLIcMqC | caching_sha2_password |
| localhost | mysql.infoschema | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| localhost | mysql.session    | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| localhost | mysql.sys        | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| localhost | root             | *43C685FF9E03403DD721CF54B4E40B199DA06624                              | mysql_native_password |
+-----------+------------------+------------------------------------------------------------------------+-----------------------+
7 rows in set (0.00 sec)

创建用户之后，默认加密类型为caching_sha2_password

Navicat登录结果：

修改用户加密方式：

mysql> alter user 'dev'@'localhost'identified with mysql_native_password by 'huluhulu';
Query OK, 0 rows affected (0.00 sec)

mysql> select host, user ,authentication_string, plugin from user;
+-----------+------------------+------------------------------------------------------------------------+-----------------------+
| host      | user             | authentication_string                                                  | plugin                |
+-----------+------------------+------------------------------------------------------------------------+-----------------------+
| %         | root             | *43C685FF9E03403DD721CF54B4E40B199DA06624                              | mysql_native_password |
| %         | test             | *43C685FF9E03403DD721CF54B4E40B199DA06624                              | mysql_native_password |
| localhost | dev              | *43C685FF9E03403DD721CF54B4E40B199DA06624                              | mysql_native_password |
| localhost | mysql.infoschema | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| localhost | mysql.session    | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| localhost | mysql.sys        | $A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED | caching_sha2_password |
| localhost | root             | *43C685FF9E03403DD721CF54B4E40B199DA06624                              | mysql_native_password |
+-----------+------------------+------------------------------------------------------------------------+-----------------------+
7 rows in set (0.00 sec)

因为可视化工具只支持旧的加密方式mysql_native_password，如果是caching_sha2_password是无法远程连接登录的

Navicat登录结果：

因为dev用户支持的是localhost登录，我们需要把他修改为远程访问机器的IP或者%，%代表任意地址

修改用户登录授权地址：

mysql> rename user 'dev'@'localhost' to 'dev'@'%';
Query OK, 0 rows affected (0.00 sec)

Navicat登录结果：

到这里我们实现访问登录，但是登录dev用户，我们发现只有一个数据库

查看dev用户权限：

mysql> show grants for 'dev'@'%';
+---------------------------------+
| Grants for dev@%                |
+---------------------------------+
| GRANT USAGE ON *.* TO `dev`@`%` |
+---------------------------------+
1 row in set (0.00 sec)

dev用户的权限为USAGE，MySQL用户权限介绍如下：

-- 权限列表
ALL [PRIVILEGES]    -- 设置除GRANT OPTION之外的所有简单权限
ALTER    -- 允许使用ALTER TABLE
ALTER ROUTINE    -- 更改或取消已存储的子程序
CREATE    -- 允许使用CREATE TABLE
CREATE ROUTINE    -- 创建已存储的子程序
CREATE TEMPORARY TABLES        -- 允许使用CREATE TEMPORARY TABLE
CREATE USER        -- 允许使用CREATE USER, DROP USER, RENAME USER和REVOKE ALL PRIVILEGES。
CREATE VIEW        -- 允许使用CREATE VIEW
DELETE    -- 允许使用DELETE
DROP    -- 允许使用DROP TABLE
EXECUTE        -- 允许用户运行已存储的子程序
FILE    -- 允许使用SELECT...INTO OUTFILE和LOAD DATA INFILE
INDEX     -- 允许使用CREATE INDEX和DROP INDEX
INSERT    -- 允许使用INSERT
LOCK TABLES        -- 允许对您拥有SELECT权限的表使用LOCK TABLES
PROCESS     -- 允许使用SHOW FULL PROCESSLIST
REFERENCES    -- 未被实施
RELOAD    -- 允许使用FLUSH
REPLICATION CLIENT    -- 允许用户询问从属服务器或主服务器的地址
REPLICATION SLAVE    -- 用于复制型从属服务器（从主服务器中读取二进制日志事件）
SELECT    -- 允许使用SELECT
SHOW DATABASES    -- 显示所有数据库
SHOW VIEW    -- 允许使用SHOW CREATE VIEW
SHUTDOWN    -- 允许使用mysqladmin shutdown
SUPER    -- 允许使用CHANGE MASTER, KILL, PURGE MASTER LOGS和SET GLOBAL语句，mysqladmin debug命令；允许您连接（一次），即使已达到max_connections。
UPDATE    -- 允许使用UPDATE
USAGE    -- “无权限”的同义词
GRANT OPTION    -- 允许授予权限

USAGE就是无权限，我们现在给dev用户添加select权限，但是只针对数据库mysql的test表，查看权限

mysql> grant select on mysql.test to 'dev'@'%' with grant option;
Query OK, 0 rows affected (0.01 sec)
mysql> show grants for 'dev'@'%';
+---------------------------------------------------------------+
| Grants for dev@%                                              |
+---------------------------------------------------------------+
| GRANT USAGE ON *.* TO `dev`@`%`                               |
| GRANT SELECT ON `mysql`.`test` TO `dev`@`%` WITH GRANT OPTION |
+---------------------------------------------------------------+
2 rows in set (0.00 sec)

Navicat登录结果：只显示一张表

修改用户加密方式：执行select语句是可以的，

SELECT * FROM test;

但是如果执行delete，或者其他DML以及DDL语句，是没有权限的

[SQL]DELETE FROM test WHERE Id=100;
[Err] 1142 - DELETE command denied to user 'dev'@'202.101.0.2' for table 'test'

后序为了测试方便，把权限赋予所有的数据库的所有表，以及添加update，select权限

mysql> grant select,update, delete on *.* to 'dev'@'%' with grant option;
Query OK, 0 rows affected (0.00 sec)

mysql> show grants for 'dev'@'%';
+--------------------------------------------------------------------+
| Grants for dev@%                                                   |
+--------------------------------------------------------------------+
| GRANT SELECT, insert, UPDATE, DELETE ON *.* TO `dev`@`%` WITH GRANT OPTION |
| GRANT SELECT ON `mysql`.`test` TO `dev`@`%` WITH GRANT OPTION      |
+--------------------------------------------------------------------+
2 rows in set (0.00 sec)

撤销dev用户delete权限：

mysql> revoke delete on *.* from 'dev'@'%';
Query OK, 0 rows affected (0.01 sec)
mysql> show grants for 'dev'@'%';
+---------------------------------------------------------------------------+
| Grants for dev@%                                                          |
+---------------------------------------------------------------------------+
| GRANT SELECT, INSERT, UPDATE, ALTER ON *.* TO `dev`@`%` WITH GRANT OPTION |
| GRANT SELECT ON `mysql`.`test` TO `dev`@`%` WITH GRANT OPTION             |
+---------------------------------------------------------------------------+
2 rows in set (0.00 sec)

撤销dev用户所有权限：

mysql> revoke all privileges on *.* from 'dev'@'%';
Query OK, 0 rows affected (0.01 sec)

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

　　PS：flush privileges命令只刷新你MySQL所在机器的权限，如果远程访问，你需要在远程操作所在的机器使用flush privileges进行

刷新权限，或者断开连接，并重新连接也会刷新

到此为止，关于一般用户权限控制的操作讲完了，包括远程访问可能遇到的问题，算是一个入门吧，希望对新手有所帮助。