默认情况下Linux内的mysql数据库mysql，user表内的用户权限只是对localhost即本机才能登陆。需要更改权限：
如下的方式确认：
root#mysql -h localhost-u mysql -p
Enter password: ******
Welcome to the MySQL monitor. Commands end with ; or /g.
Your MySQL connection id is 4 to server version: 4.0.20a-debug
Type 'help;' or '/h' for help. Type '/c' to clear the buffer.
mysql> use mysql; (此DB存放MySQL的各种配置信息)
Database changed
mysql> select host,user from user; (查看用户的权限情况)
+-------------+-------+
| host | user |
+-------------+-------+
| localhost | |
| localhost | root |
| localhost | |
| localhost | mysql |
+-------------+-------+
6 rows in set (0.02 sec)
由此可以看出，只能以localhost的主机方式访问。
解决方法：
mysql> Grant all privileges on *.* to 'root'@'%' identified by ‘password’with grant option;
(%表示是所有的外部机器，如果指定某一台机，就将%改为相应的机器名；‘root’则是指要使用的用户名，)
mysql> flush privileges; (运行为句才生效，或者重启MySQL)
Query OK, 0 rows affected (0.03 sec)
mysql> select host,user from user; (再次查看用户的权限情况)
+-------------+-------+
| host | user |
+-------------+-------+
| ％ | mysql |
| ％ | root |
| localhost | |
| localhost | root |
| localhost | |
| localhost | mysql |
+-------------+-------+
mysql>exit
现在再试试：
root#mysql -h mysql -u root -p
Enter password:******
Welcome to the MySQL monitor. Commands end with ; or /g.
Your MySQL connection id is 9 to server version: 4.0.20a-debug
Type 'help;' or '/h' for help. Type '/c' to clear the buffer.
mysql>
就成功连接上了。