在ORACLE测试服务器上还原恢复了一个数据库后，启动监听服务时出现了TNS-12541, TNS-12560,TNS-00511之类的错误，具体情况如下所示：

[oracle@getlnx01 admin]$ lsnrctl status

LSNRCTL for Linux: Version 10.2.0.4.0 - Production on 09-MAR-2015 09:13:29

Copyright (c) 1991, 2007, Oracle. All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1)))

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=TCP)(HOST=getlnx01.esqule.com)(PORT=1521)))

TNS-12541: TNS:no listener

TNS-12560: TNS:protocol adapter error

TNS-00511: No listener

Linux Error: 111: Connection refused

[oracle@getlnx01 dbs]$ lsnrctl start

LSNRCTL for Linux: Version 10.2.0.4.0 - Production on 09-MAR-2015 09:20:46

Copyright (c) 1991, 2007, Oracle. All rights reserved.

Starting /u01/app/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait...

TNSLSNR for Linux: Version 10.2.0.4.0 - Production

System parameter file is /u01/app/oracle/product/10.2.0/db_1/network/admin/listener.ora

Log messages written to /u01/app/oracle/product/10.2.0/db_1/network/log/listener.log

Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1)))

Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=getlnx01.esqule.com)(PORT=1521)))

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1)))

TNS-12547: TNS:lost contact

TNS-12560: TNS:protocol adapter error

TNS-00517: Lost contact

Linux Error: 104: Connection reset by peer

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=getlnx01.esqule.com)(PORT=1521)))

TNS-12541: TNS:no listener

TNS-12560: TNS:protocol adapter error

TNS-00511: No listener

Linux Error: 111: Connection refused

　　因为曾经遇到并解决过TNS-12541这类错误，立即检查/etc/hosts文件，结果发现IP地址写错了，正确的IP地址应该为192.168.7.221,而不是粗心手误写错的192.168.7.211

　　[root@getlnx01 ~]# more /etc/hosts

　　# Do not remove the following line, or various programs

　　# that require network functionality will fail.

　　127.0.0.1 getlnx01.esqule.com getlnx01

　　192.168.7.211 getlnx01.esqule.com getlnx01

　　修改为正确的IP地址后，依然出现这个错误，后面查看了官方文档Starting TNS Listener or LSNRCTL Start Yields TNS-12541, Linux Error: 111: Connection Refused (文档 ID 343295.1)后，才发现是因为本地主机环回名称和地址不正确所致，修改/etc/hosts后，重启监听服务，问题解决。

[oracle@getlnx01 ~]$ more /etc/hosts

# Do not remove the following line, or various programs

# that require network functionality will fail.

127.0.0.1 localhost.localdomain localhost

192.168.7.221 getlnx01.esqule.com getlnx01

CAUSE

1. There is possibly an incorrect IP Address specified for the host in the /etc/hosts file.

For example:

192.168.101.101 prod1.us.oracle.com prod1

Whereas the actual ip address for the host "prod1.us.oracle.com" is 192.168.101.110

2. Also, the localhost reference may be incorrect or missing from the /etc/hosts file.

3. Oracle may not have read access to /etc/nsswitch.conf file.

SOLUTION

To implement the solution, please execute the following steps:

1. Correct the mapping in the /etc/hosts file by adding/correcting the IP address and/or hostname reference for the Unix/Linux Server (both long and short host names).

For example:

# Add or edit the /etc/hosts file to include a valid entry for the Server:

192.168.101.110 prod1.us.oracle.com prod1

2. Check that the localhost loopback name and address are correct (both long and short host names).

An example of a correct localhost entry would be as follows:

127.0.0.1 localhost.localdomain localhost

3. Remember to save the /etc/hosts file and then start the listener.

4. Check permissions on /etc/nsswitch.conf file to ensure group and other have read access.

- If necessary change permisions on /etc/nsswitch.conf as follows:

chmod 644 /etc/nsswitch.conf

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