ERROR 2003 (HY000): Can't connect to MySQL server on '172.27.9.252' (110 "Connection timed out")

新安装了MariaDB，本机能够连接，但是无法远程连接：
ERROR 2003 (HY000): Can’t connect to MySQL server on ‘172.27.9.252’ (110 “Connection timed out”)

[root@moxiaokai ~]# mysql -h 127.0.0.1 -uroot -p
Enter password: 
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 12
Server version: 10.1.13-MariaDB Source distribution

Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.


[root@moxiaokai ~]# mysql -h 172.27.9.252 -uroot -p
Enter password: 
ERROR 2003 (HY000): Can't connect to MySQL server on '172.27.9.252' (110 "Connection timed out")
[root@moxiaokai mydata]# perror 111
OS error code 111:  Connection refused

问题分析：
1.排除网络问题(127.0.0.1能够访问)
2.排除防火墙问题(防火墙已关闭)
3.检查日志(无错误日志)
4.排查配置问题(检查/etc/my.cnf)
根本原因：
数据库配置问题，没有启用[client],在/etc/my.cnf配置文件中添加以下配置，重启数据库。

[client]
port            = 3306
socket          = /data/sdv1/mydata/mariadb.sock