在查看alert日志的时候发现：
1 *********************************************************************** 2 3 Fatal NI connect error 12170. 4 5 VERSION INFORMATION: 6 TNS for Linux: Version 11.2.0.1.0 - Production 7 Oracle Bequeath NT Protocol Adapter for Linux: Version 11.2.0.1.0 - Production 8 TCP/IP NT Protocol Adapter for Linux: Version 11.2.0.1.0 - Production 9 Time: 27-DEC-2012 16:17:46 10 Tracing not turned on. 11 Tns error struct: 12 ns main err code: 12535 13 14 TNS-12535: TNS:operation timed out 15 ns secondary err code: 12560 16 nt main err code: 505 17 18 TNS-00505: Operation timed out 19 nt secondary err code: 110 20 nt OS err code: 0 21 Client address: (ADDRESS=(PROTOCOL=tcp)(HOST=xxx.xxx.xxx.xxx)(PORT=xxxx)) 22 Thu Dec 27 16:46:44 2012 23 24 25 ***********************************************************************
参考官方说明关于该警告的说明：
Note:465043.1
The "WARING:inbound connection timed out (ORA-3136)" in the alert log indicates that the client was not able to complete it's authentication within the period of time specified by parameter SQLNET.INBOUND_CONNECT_TIMEOUT.
You may also witness ORA-12170 without timeout error on the database sqlnet.log file.This entry would also have the client address which failed to get authenticated.Some applications or JDBC thin driver applications may not have these details.
可能的原因：
1、网络攻击，例如：半开连接攻击
Server gets a connection request from a malcious client which is not supposed to connect to the database,in which case the error thrown is the correct behavior.You can get the client address for which the error was thrown via sqlnet log file.
2、Client在default 60秒内没有完成认证
The server receives a valid client connection request but the client tabkes a long time to authenticate more than the default 60 seconds.
3、DB负载太高
The DB server is heavily loaded due to which it cannot finish the client logon within the timeout specified.
WANGING:inbound connection timed out (ORA-3136)
解决问题：
其实这个参数跟监听的一个参数有关：SQLNET.INBOUND_CONNECT_TIMEOUT
这个参数从9i开始引入，指定了客户端连接服务器并且提供认证信息的超时时间，如果超过这个时间客户端没有提供正确的认证信息，服务器会自动中止连接请求，同时会记录试图连接的IP地址和ORA-12170：TNS:Connect timeout occurred错误。
这个参数的引入，主要是防止DoS攻击，恶意攻击者可以通过不停的开启大量连接请求，占用服务器的连接资源，使得服务器无法提供有效服务。在10.2.0.1起，该参数默认设置为60秒。
但是，这个参数的引入也导致了一些相关的Bug。比如：
Bug 5594769 - REMOTE SESSION DROPPED WHEN LOCAL SESSION SHARED AND INBOUND_CONNECT_TIMEOUT SET
Bug 5249163 - CONNECTS REFUSED BY TNSLSNR EVERY 49 DAYS FOR INBOUND_CONNEC_TIMEOUT SECONDS
该参数可以通过设置为0来禁用，在服务端：
1)、设置sqlnet.ora文件：SQLNET.INBOUND_CONNECT_TIMEOUT=0；
2)、设置listener.ora文件：INBOUND_CONNECT_TIMEOUT_listenername=0；
3)、然后reload或者重启监听。
说明：这是由于连接超时所产生的问题，在10.2.0.1.0版本中sqlnet.inbound_connect_timeout参数默认为60秒，即如果连接时间超过60秒则提示超时，而在其他版本中这两个参数默认为0，即无限制。
具体操作例子:
----因为之前修改了很多次参数，一直没成功，这次就索性把监听给停掉了----------------
1 [oracle@cnbpi admin]$ lsnrctl stop 2 3 LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 27-DEC-2012 22:40:24 4 5 Copyright (c) 1991, 2009, Oracle. All rights reserved. 6 7 Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=xxxx)(PORT=xxxx))) 8 The command completed successfully ----在sqlnet.ora文件中添加SQLNET.INBOUND_CONNECT_TIMEOUT = 0----------
9 [oracle@cnbpi admin]$ vi sqlnet.ora 10 # sqlnet.ora Network Configuration File: /u01/app/oracle/product/11.2.0/db_1/network/admin/sqlnet.ora 11 # Generated by Oracle configuration tools. 12 13 NAMES.DIRECTORY_PATH= (TNSNAMES) 14 SQLNET.INBOUND_CONNECT_TIMEOUT = 0 15 ----在listener.ora文件添加INBOUND_CONNECT_TIMEOUT_listener=0------------
16 [oracle@cnbpi admin]$ vi listener.ora 17 18 # listener.ora Network Configuration File: /u01/app/oracle/product/11.2.0/db_1/network/admin/listener.ora 19 # Generated by Oracle configuration tools. 20 21 LISTENER = 22 (DESCRIPTION_LIST = 23 (DESCRIPTION = 24 (ADDRESS = (PROTOCOL = TCP)(HOST = cnbpi)(PORT = xxxx)) 25 # (CONNECT_TIMEOUT_LISTENER = 3600) -------该参数在测试中不起作用 26 ) 27 ) 28 INBOUND_CONNECT_TIMEOUT_listener=0 29 30 [oracle@cnbpi admin]$ lsnrctl 31 32 LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 27-DEC-2012 22:42:14 33 34 Copyright (c) 1991, 2009, Oracle. All rights reserved. 35 36 Welcome to LSNRCTL, type "help" for information. 37 -----因为监听已经停止，所以查不出inbound_connect_timeout参数是否修改成功----------------
38 LSNRCTL> show inbound_connect_timeout 39 Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=cnbpi)(PORT=1521))) 40 TNS-12541: TNS:no listener 41 TNS-12560: TNS:protocol adapter error 42 TNS-00511: No listener 43 Linux Error: 111: Connection refused 44 LSNRCTL> set inbound_connect_timeout 0 45 Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=cnbpi)(PORT=1521))) 46 TNS-12541: TNS:no listener 47 TNS-12560: TNS:protocol adapter error 48 TNS-00511: No listener 49 Linux Error: 111: Connection refused ----启动监听-----------------------------------
50 LSNRCTL> start 51 Starting /u01/app/oracle/product/11.2.0/db_1/bin/tnslsnr: please wait... 52 53 TNSLSNR for Linux: Version 11.2.0.1.0 - Production 54 System parameter file is /u01/app/oracle/product/11.2.0/db_1/network/admin/listener.ora 55 Log messages written to /u01/app/oracle/diag/tnslsnr/cnbpi/listener/alert/log.xml 56 Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=cnbpi)(PORT=xxxx))) 57 58 Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=cnbpi)(PORT=xxxx))) 59 STATUS of the LISTENER 60 ------------------------ 61 Alias LISTENER 62 Version TNSLSNR for Linux: Version 11.2.0.1.0 - Production 63 Start Date 27-DEC-2012 22:42:37 64 Uptime 0 days 0 hr. 0 min. 0 sec 65 Trace Level off 66 Security ON: Local OS Authentication 67 SNMP OFF 68 Listener Parameter File /u01/app/oracle/product/11.2.0/db_1/network/admin/listener.ora 69 Listener Log File /u01/app/oracle/diag/tnslsnr/cnbpi/listener/alert/log.xml 70 Listening Endpoints Summary... 71 (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=cnbpi)(PORT=xxxx))) 72 The listener supports no services 73 The command completed successfully ----查看inbound_connect_timeout参数已经修改成功，值为0-------------------
74 LSNRCTL> show inbound_connect_timeout 75 Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=xxxx)(PORT=xxxx))) 76 LISTENER parameter "inbound_connect_timeout" set to 0 77 The command completed successfully
-----因为之前在修改中可能是参数设置不对，所以一直没成功，所以用了这种最笨的方法使监听停掉以后再修改，其实只需修改了参数以后再reload一下就可以了。
参考文档：
