监听器也有安全？sure！在缺省的情况下，任意用户不需要使用任何密码即通过lsnrctl 工具对oracle listener进行操作或关闭，从而造成任意新的会话都将无法建立连接。在oracle 9i 中oracle监听器允许任何一个人利用lsnrctl从远程发起对监听器的管理。也容易导致数据库受到损坏。
1. 未设定密码情形下停止监听
[oracle@test ~]$ lsnrctl stop listener_demo92 -->停止监听，可以看出不需要任何密码即可停止
lsnrctl for linux: version 9.2.0.8.0 - production on 26-jun-2011 08:22:26
copyright (c) 1991, 2006, oracle corporation. all rights reserved.
connecting to (description=(address=(protocol=tcp)(host=test)(port=1521)))
the command completed successfully
2. 重新启动监听并设置密码
[oracle@test ~]$ lsnrctl
lsnrctl for linux: version 9.2.0.8.0 - production on 26-jun-2011 08:24:09
copyright (c) 1991, 2006, oracle corporation. all rights reserved.
welcome to lsnrctl, type "help" for information.
lsnrctl> set current_listener listener_demo92 -->设置当前监听器
current listener is listener_demo92
lsnrctl> start -->启动过程也不需要任何密码,启动的详细信息省略
lsnrctl> change_password -->使用change_password来设置密码
old password:
new password:
reenter new password:
connecting to (description=(address=(protocol=tcp)(host=test)(port=1521)))
password changed for listener_demo92
the command completed successfully
lsnrctl> save_config -->注意此处的save_config失败
connecting to (description=(address=(protocol=tcp)(host=test)(port=1521)))
tns-01169: the listener has not recognized the password
lsnrctl> set password -->输入新设定的密码验证
password:
the command completed successfully
lsnrctl> save_config -->再次save_config成功
connecting to (description=(address=(protocol=tcp)(host=test)(port=1521)))
saved listener_demo92 configuration parameters.
listener parameter file /oracle/92/network/admin/listener.ora
old parameter file /oracle/92/network/admin/listener.bak
the command completed successfully
-->增加密码之后可以看到listener.ora文件中有一条新增的记录，即密码选项(注：尽管使用了密码管理方式,仍然可以无需密码启动监听)
[oracle@test admin]$ more listener.ora
#----added by tnslsnr 26-jun-2011 05:12:48---
passwords_listener_demo92 =
#--------------------------------------------
3. 尝试未使用密码的情况下停止监听
[oracle@test ~]$ lsnrctl stop listener_demo92
lsnrctl for linux: version 9.2.0.8.0 - production on 26-jun-2011 06:09:51
copyright (c) 1991, 2006, oracle corporation. all rights reserved.
connecting to (description=(address=(protocol=tcp)(host=test)(port=1521)))
tns-01169: the listener has not recognized the password -->收到错误信息，需要使用密码认证
4. 使用密码来停止监听
[oracle@test ~]$ lsnrctl lsnrctl> set current_listener listener_demo92 current listener is listener_demo92 lsnrctl> stop connecting to (description=(address=(protocol=tcp)(host=test)(port=1521))) tns-01169: the listener has not recognized the password lsnrctl> set password password: the command completed successfully lsnrctl> stop connecting to (description=(address=(protocol=tcp)(host=test)(port=1521))) the command completed successfully lsnrctl> status connecting to (description=(address=(protocol=tcp)(host=test)(port=1521))) tns-12541: tns:no listener tns-12560: tns:protocol adapter error tns-00511: no listener linux error: 111: connection refused connecting to (description=(address=(protocol=ipc)(key=extproc))) tns-12541: tns:no listener tns-12560: tns:protocol adapter error tns-00511: no listener linux error: 2: no such file or directory
5. save_config失败的问题
-->在 oracle 9i中，使用save_config命令将会失败
lsnrctl> save_config
connecting to (description=(address=(protocol=tcp)(host=<hostname>)(port=<port>)))
tns-01169: the listener has not recognized the password
-->应该先使用set password之后再save_config，则保存配置成功。
lsnrctl> set password
password: <the password you chose>
the command completed successfully
/*在oracle 10g 中不会出现类似的问题，因为在10g中可以使用基于操作系统验证方式。listener将检测到如果用户属于dba组的成员，
将会被授予改变密码，保存配置以及停止监听等权限。 */
6. 配置listener.ora中admin_restrictions参数
参数作用：
当在listener.ora文件中设置了admin_restrictions参数后，在监听器运行时，不允许执行任何管理命令，同时set命令将不可用
，不论是在服务器本地还是从远程执行都不行。此时对于监听的设置仅仅通过手工修改listener.ora文件，要使修改生效，只能
使用lsnrctl reload命令或lsnrctl stop/start命令重新载入一次监听器配置信息。
修改方法：
在listener.ora文件中手动加入下面这样一行
admin_restrictions_<监听器名> = on
下面是其它网友的补充：
lsnrctl> change_password
old password:
new password:
reenter new password:
connecting to (description=(address=(protocol=tcp)(host=ecp-uc-db1)(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=ecp-uc-db1)(port=1521)))
saved listener configuration parameters.
listener parameter file /opt/oracle/product/10.2.0/db_1/network/admin/listener.ora
old parameter file /opt/oracle/product/10.2.0/db_1/network/admin/listener.bak
the command completed successfully
[oracle@ecp-uc-db1 admin]$ cat listener.ora
#—-added by tnslsnr 10-jun-2011 18:13:24—
passwords_listener = 6d7aa003392c436a
#——————————————–
note：10g数据库上需要上添加（重启监听）
local_os_authentication_listener = off
1、添加local_os_authentication_listener = off之前
security on: password or local os authentication
2、添加local_os_authentication_listener = off之后
security on: password
lsnrctl> status
connecting to (description=(address=(protocol=tcp)(host=ecp-uc-db1)(port=1521)))
tns-01169: the listener has not recognized the password
lsnrctl> stop
connecting to (description=(address=(protocol=tcp)(host=ecp-uc-db1)(port=1521)))
tns-01169: the listener has not recognized the password
lsnrctl> set password 123456
the command completed successfully
lsnrctl> status
connecting to (description=(address=(protocol=tcp)(host=ecp-uc-db1)(port=1521)))
status of the listener
————————
alias listener
version tnslsnr for linux: version 10.2.0.4.0 – production
start date 10-jun-2011 18:15:49
uptime 0 days 0 hr. 1 min. 16 sec
trace level off
security on: password
snmp off
listener parameter file /opt/oracle/product/10.2.0/db_1/network/admin/listener.ora
listener log file /opt/oracle/product/10.2.0/db_1/network/log/listener.log
listening endpoints summary…
(description=(address=(protocol=tcp)(host=ecp-uc-db1)(port=1521)))
(description=(address=(protocol=ipc)(key=extproc0)))
services summary…
service “plsextproc” has 1 instance(s).
instance “plsextproc”, status unknown, has 1 handler(s) for this service…
service “ecp” has 1 instance(s).
instance “ecp”, status ready, has 1 handler(s) for this service…
service “ecpxdb” has 1 instance(s).
instance “ecp”, status ready, has 1 handler(s) for this service…
service “ecp_xpt” has 1 instance(s).
instance “ecp”, status ready, has 1 handler(s) for this service…
the command completed successfully