HOST is not allowed to connect to this mysql server

host主机不能访问本机的mysql服务，原因需要连接非本机的mysql的时候，默认host是localhost，我们需要将这个mysql连接权限设置成%，更改方法直接通过软件更改和命令行更改：
在mysql的数据库选择mysql这个数据库，里面有一个user表，进入表中有一个host字段将localhost值更改为%这个保存后，刷新或者重启MySQL服务都行。
登录服务器mysql查看

mysql> use mysql;
Database changed
mysql> 
mysql> select host,user from user;
+-----------+------------------+
| host      | user             |
+-----------+------------------+
| localhost | mysql.infoschema |
| localhost | mysql.session    |
| localhost | mysql.sys        |
| localhost | root             |
+-----------+------------------+
4 rows in set (0.00 sec)

mysql>

授权访问,因为是本地连接,所以,给予了所有权限

mysql> grant all privileges on *.* to 'root'@'%' with grant option;
ERROR 1410 (42000): You are not allowed to create a user with GRANT

报错，产生用户不能授权的原因是mysql 数据库中user 表中的特定用户(root) 的host 的属性值为localhost.

mysql> 
mysql> update user set host='%' where user='root';
Query OK, 1 row affected (0.01 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> 
mysql> 
mysql> grant all privileges on *.* to 'root'@'%';
Query OK, 0 rows affected (0.01 sec)

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

mysql>

然后测试连接又报错了，提示说：“客户端不支持服务器请求的身份验证协议”

 更改加密方式

  mysql> alter user 'root'@'%' identified by '111111' password expire never;
  Query OK, 0 rows affected (0.01 sec)

  mysql>

更改密码

mysql> alter user 'root'@'%' identified with mysql_native_password by '111111';
Query OK, 0 rows affected (0.00 sec)

mysql>

刷新权限

mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)

mysql>

连接成功