修改密码如下：

[oracle@rhel55 ~]$ sqlplus /nolog

SQL*Plus: Release 11.2.0.1.0 Production on 星期二 2月 7 09:35:58 2012

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

SQL> conn /as sysdba
已连接。
SQL> alter user sys identified by oracle123;

用户已更改。

SQL> alter user system identified by oracle123;

用户已更改。

SQL> exit
从 Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 – Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options 断开
[oracle@rhel55 ~]$

[oracle@rhel55 ~]$ sqlplus

SQL*Plus: Release 11.2.0.1.0 Production on 星期二 2月 7 09:39:16 2012

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

请输入用户名:  system
输入口令:   //刚才设置的密码

连接到:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 – Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL>