Ubuntu Server中LAMP下MySQL无法远程连接该怎么办：
很常见的问题发生了，我们怎么处理它?
环境：ubuntu Server (版本8.04以上对于LAMP应用都大同小异), cl@ubuntu.
目的：安装LAMP重新配置RT系统。
软件：服务器端已安装LAMP组件，MySQL5.1版本;客户端使用Navicat进行远程连接。
问题② 提示”is not allowed to connect to this MySQL server” ,如图2
对于数据库的远程连接不外乎两方面入手：1、客户端至服务器端的连通性。2、服务器端没有合理配置。当然非要加上客户端也没有配置之类的，也尚可，比如ODBC的方式连接MySQL。
②当MySQL 连接服务器时发生”is not allowed to connect to this MySQL server”错误，我们要注意在MySQL的user表中修改host列的localhost为%，即可以远程连接。
做如下操作：
mysql> use mysql --切换数据库上下文
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> select host,user,password from user; --查询USER 表
+-----------+------------------+-------------------------------------------+
- | host | user | password |
+-----------+------------------+-------------------------------------------+
- | localhost | root | *MD5加密 |
- | ubuntu | root | *MD5加密 |
- | 127.0.0.1 | root | *MD5加密 |
- | localhost | debian-sys-maint | * MD5加密|
+-----------+------------------+-------------------------------------------+
- mysql> delete from user where user='root' and host <> '%'; --删除多余用户
- Query OK, 2 rows affected (0.00 sec)
- mysql> update user set host ='%' where host='localhost' and user='root'; --更新host
- Query OK, 1 row affected (0.00 sec)
- Rows matched: 1 Changed: 1 Warnings: 0
- mysql> select host,user,password from user;
+-----------+------------------+-------------------------------------------+
| host | user | password |
+-----------+------------------+-------------------------------------------+
| % | root | *MD5加密|
| localhost | debian-sys-maint | * MD5加密|
+-----------+------------------+-------------------------------------------+
2 rows in set (0.00 sec)
注：如果在修改User时失误出现以下结果，怎么办?
mysql> select host,user,password from user;
+-----------+------------------+-------------------------------------------+
| host | user | password |
+-----------+------------------+-------------------------------------------+
| ubuntu | root | * MD5加密|
| localhost | debian-sys-maint | * MD5加密|
+-----------+------------------+-------------------------------------------+
2 rows in set (0.00 sec)
此时没有127.0.0.1和localhost主机，所以无法用root用户进行连接，会提示以下错误
- ~$ mysql -u root -p
- Enter password:
- ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
则此时只能用系统自带的debian-sys-maint用户登录，修改host。该用户的的登录密码在/etc/mysql/debian.cnf中明文显示。
比如：
- host = localhost
- user = debian-sys-maint
- password = 明文密码
- socket = /var/run/mysqld/mysqld.sock
- basedir = /usr
做如下操作：
- ~$ mysql -u debian-sys-maint -p
- Enter password:
- mysql> use mysql;
- mysql> update user set host ='%' where host='ubuntu';
- mysql> exit
- ~$ sudo /etc/init.d/mysql restart
清理思路，注意操作后需重启服务。
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