很多人都知道，Oracle的监听器一直存在着一个安全隐患，假如不设置安全措施，那么能够访问的用户就可以远程关闭监听器。
相关示例：
D:\>lsnrctl stop eygle
LSNRCTL for 32-bit Windows: Version 10.2.0.3.0 - Production on 28-11月-2007 10:02:40
Copyright (c) 1991, 2006, Oracle. All rights reserved.
正在连接到 (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=172.16.33.11)(PORT=1521))
(CONNECT_DATA=(SERVICE_NAME=eygle)))
命令执行成功
大家可以发现，此时缺省的监听器的日志还无法记录操作地址：
No longer listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=172.16.33.11)(PORT=1521)))
28-NOV-2007 09:59:20 * (CONNECT_DATA=(CID=(PROGRAM=)(HOST=)(USER=Administrator))(COMMAND=stop)
(ARGUMENTS=64)(SERVICE=eygle)(VERSION=169870080)) * stop * 0
为了更好的保证监听器的安全，大家最好为监听设置密码：
[oracle@jumper log]$ lsnrctl
LSNRCTL for Linux: Version 9.2.0.4.0 - Production on 28-NOV-2007 10:18:17
Copyright (c) 1991, 2002, Oracle Corporation. All rights reserved.
Welcome to LSNRCTL, type "help" for information.
LSNRCTL> set current_listener listener
Current Listener is listener
LSNRCTL> change_password
Old password:
New password:
Reenter new password:
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=172.16.33.11)(PORT=1521)))
Password changed for listener
The command completed successfully
LSNRCTL> set password
Password:
The command completed successfully
LSNRCTL> save_config
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=172.16.33.11)(PORT=1521)))
Saved LISTENER configuration parameters.
Listener Parameter File /opt/oracle/product/9.2.0/network/admin/listener.ora
Old Parameter File /opt/oracle/product/9.2.0/network/admin/listener.bak
The command completed successfully
在我们设置密码后，远程操作将会因缺失密码而出现失败：
D:\>lsnrctl stop eygle
LSNRCTL for 32-bit Windows: Version 10.2.0.3.0 - Production on 28-11月-2007 10:22:57
Copyright (c) 1991, 2006, Oracle. All rights reserved.
正在连接到 (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=172.16.33.11)
(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=eygle)))
TNS-01169: 监听程序尚未识别口令
注意：此时在服务器端或客户端，都需要我们通过密码来起停监听器：
LSNRCTL> set password
Password:
The command completed successfully
LSNRCTL> stop
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=172.16.33.11)(PORT=1521)))
The command completed successfully
LSNRCTL> start
Starting /opt/oracle/product/9.2.0/bin/tnslsnr: please wait...
TNSLSNR for Linux: Version 9.2.0.4.0 - Production
System parameter file is /opt/oracle/product/9.2.0/network/admin/listener.ora
Log messages written to /opt/oracle/product/9.2.0/network/log/listener.log
Trace information written to /opt/oracle/product/9.2.0/network/trace/listener.trc
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=172.16.33.11)(PORT=1521)))
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=172.16.33.11)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for Linux: Version 9.2.0.4.0 - Production
Start Date 28-NOV-2007 10:22:23
Uptime 0 days 0 hr. 0 min. 0 sec
Trace Level support
Security ON
SNMP OFF
Listener Parameter File /opt/oracle/product/9.2.0/network/admin/listener.ora
Listener Log File /opt/oracle/product/9.2.0/network/log/listener.log
Listener Trace File /opt/oracle/product/9.2.0/network/trace/listener.trc
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=172.16.33.11)(PORT=1521)))
Services Summary...
Service "eygle" has 1 instance(s).
Instance "eygle", status UNKNOWN, has 1 handler(s) for this service...
Service "julia" has 1 instance(s).
Instance "eygle", status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully
另外，ADMIN_RESTRICTIONS参数也是一个重要的安全选项，大家可以在 listener.ora 文件中设置 ADMIN_RESTRICTIONS_ 为 ON，此后所有在运行时对监听器的修改都将会被阻止，所有对监听器的修改都必须通过手工修改listener.ora文件才能顺利完成