1、编辑 my.cnf 文件：
sudo vi /etc/mysql/my.cnf
2、将绑定地址行注释掉或者修改为指定 IP
#bind-address = 127.0.0.1
3、登录 MySQL：
mysql -uroot -p密码
4、添加 root 用户访问权限
grant all privileges on *.* to 'root'@'%' identified by '密码';
flush privileges;
5、查看 user 权限，成功修改权限为 %：
select host,user from mysql.user;
+------------+----------------+
| host | user |
+------------+----------------+
| % | root |
| 127.0.0.1 | root |
| localhost | root |
+------------+----------------+
6、重启 MySQL：
sudo /etc/init.d/mysql restart