Mariadb远程登陆配置及相关问题排查

前言：

　　安装过程不再赘述，直接说问题，mysql的远程连接需要解决两个问题：1.允许root用户远程连接。2.允许任意ip远程连接数据库。当然，在测试和解决问题之前，得首先保证你的数据库与远程主机之间的网络通信没有问题，简单的来说，就是互相ping通，其次，为了避免防火墙的干扰，将本地主机和数据库主机的防火墙都关闭，当然，生产环境下防火墙肯定是要打开的，并且需要额外的安全配置。

问题解决：

1.新安装的数据库默认是需要初始化的，在数据库服务启动的情况下，使用下面的命令来进行初始化。

[root@localhost ~]# mysql_secure_installation
New password: 
Re-enter new password: 
Password updated successfully!
Reloading privilege tables..
 ... Success!


By default, a MariaDB installation has an anonymous user, allowing anyone
to log into MariaDB without having to have a user account created for
them.  This is intended only for testing, and to make the installation
go a bit smoother.  You should remove them before moving into a
production environment.

Remove anonymous users? [Y/n] 
 ... Success!

Normally, root should only be allowed to connect from 'localhost'.  This
ensures that someone cannot guess at the root password from the network.

Disallow root login remotely? [Y/n] n　　#如果是为root用户配置远程登陆，这里需要选择n，不选择禁止root用户远程登陆，别的选择都无关紧要。
 ... skipping.

By default, MariaDB comes with a database named 'test' that anyone can
access.  This is also intended only for testing, and should be removed
before moving into a production environment.

Remove test database and access to it? [Y/n] 
 - Dropping test database...
 ... Success!
 - Removing privileges on test database...
 ... Success!

Reloading the privilege tables will ensure that all changes made so far
will take effect immediately.

Reload privilege tables now? [Y/n] 
 ... Success!

Cleaning up...

All done!  If you've completed all of the above steps, your MariaDB
installation should now be secure.

Thanks for using MariaDB!
[root@localhost ~]# systemctl restart mariadb　　#完成初始化之后，重启服务。

2.允许root用户远程连接与允许任意ip远程连接数据库都是可以通过在数据库里执行一条命令来实现的。

这里分为两种情况：

1）新建admin用户远程连接mysql数据库（新建任意用户，以admin为例）

grant all on *.* to admin@'%' identified by '123456' with grant option;
flush privileges;

允许任何ip地址(%表示允许任何ip地址)的电脑用admin帐户和密码(123456)来访问这个mysql server。
注意admin账户不一定要存在。

2）支持root用户允许远程连接mysql数据库

grant all privileges on *.* to 'root'@'%' identified by '123456' with grant option;
flush privileges;

需要注意的是，为root用户配置远程登陆，密码需要和之前配置的密码一致。

3.ubuntu系统的额外配置。

Ubuntu系统的my.cnf文件在vim /etc/mysql/mysql.conf.d/mysqld.cnf中，注释掉其中的

bind-address           = 127.0.0.1

centos系统的配置文件中默认没有该行。

检查的办法也很简单，在数据库启动的前提下，使用netstat -an | grep 3306查看端口的连接信息。0.0.0.0则表示允许任意IP连接。

 如图所示则为允许任意IP连接。