MySQL 8 allows remote hosts to connect the local server

Environmental Information

Ubuntu version information:

$ lsb_release --all
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 18.04.3 LTS
Release:	18.04
Codename:	bionic

MySQL version information:

$ mysql --version
mysql  Ver 8.0.19 for Linux on x86_64 (MySQL Community Server - GPL)

New accounts, assign permissions

By default, MySQL only allows local connections, view mysqlthe database usertable, you can see all users connect to the server only allows localhost:

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)

We can create a new account:

mysql> create user 'root'@'192.168.1.4' // 'user_name'@'host_name'
    -> identified by 'password'; // 密码
Query OK, 0 rows affected (0.09 sec)

The above command, said: create an account, user name root, password password, IP to allow 192.168.1.4the host to connect to the machine MySQL server.

The new account is added to the mysqldatabase usertable:

mysql> select host,user from user;
+-------------+------------------+
| host        | user             |
+-------------+------------------+
| 192.168.1.4 | root             |
| localhost   | mysql.infoschema |
| localhost   | mysql.session    |
| localhost   | mysql.sys        |
| localhost   | root             |
+-------------+------------------+
5 rows in set (0.00 sec)

Then assign permissions to the account:

mysql> GRANT ALL // 所有权限
    -> ON *.* // 任意数据库的任意表
    -> TO 'root'@'192.168.1.4'; // 给那一个账户
Query OK, 0 rows affected (0.11 sec)

Open ports

Check the status of the firewall:

$ sudo ufw status
[sudo] password for mk: 
Status: active

To                         Action      From
--                         ------      ----
22                         ALLOW       Anywhere                     
22 (v6)                    ALLOW       Anywhere (v6)

We need to open TCP port 3306 protocol:

$ sudo ufw allow 3306/tcp
Rule added
Rule added (v6)

Reload the firewall rules:

$ sudo ufw reload
Firewall reloaded

Check firewall status again:

$ sudo ufw status 
Status: active

To                         Action      From
--                         ------      ----
22                         ALLOW       Anywhere                  
3306/tcp                   ALLOW       Anywhere                  
22 (v6)                    ALLOW       Anywhere (v6)             
3306/tcp (v6)              ALLOW       Anywhere (v6)

After completion of the above operations, the designated IP remote clients can connect to the machine MySQL server through the account.