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 (0.00sec)
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 (0.00sec)
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 (0.01sec)
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 (0.00sec)
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 (0.01sec)
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 (0.01sec)
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。
