客户端连接oracle无服务器提示ORA-12537：TNS:连接关闭

  今天有个朋友出现了这么一个情况，在使用pl/sql连接数据库的时候提示ORA-12537：TNS:连接关闭。

查看过程（为了保密，特模拟过程）：

查看过程：

1）查看客户端tnsname.ora文件信息如下：

# tnsnames.ora Network Configuration File: E:\softsetup\oracle_client\oracle_base\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.

RHYS =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.101)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVICE_NAME = RHYS)
    )
  )

没有问题

2）查看服务器监听状态

[oracle@oracle-one ~]$ lsnrctl status

LSNRCTL for Linux: Version 11.2.0.4.0 - Production on 01-NOV-2013 11:19:35

Copyright (c) 1991, 2013, Oracle.  All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=oracle-one)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 11.2.0.4.0 - Production
Start Date                01-NOV-2013 11:08:41
Uptime                    0 days 0 hr. 10 min. 54 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /opt/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora
Listener Log File         /opt/app/oracle/diag/tnslsnr/oracle-one/listener/alert/log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=oracle-one)(PORT=1521)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521)))
Services Summary...
Service "RHYS" has 1 instance(s).
  Instance "RHYS", status READY, has 1 handler(s) for this service...
Service "RHYSXDB" has 1 instance(s).
  Instance "RHYS", status READY, has 1 handler(s) for this service...
The command completed successfully
[oracle@oracle-one ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Fri Nov 1 11:19:38 2013

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> show parameter service

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
service_names                        string      RHYS