WARNING: inbound connection timed out (ORA-3136)

转载过一篇介绍这个问题的文章，参见：http://chinadm123.blog.51cto.com/3952657/1122160

检查数据库alert日志发现有warning：

Fatal NI connect error 12170.

  VERSION INFORMATION:
        TNS for Linux: Version 11.2.0.2.0 - Production
        Oracle Bequeath NT Protocol Adapter for Linux: Version 11.2.0.2.0 - Production
        TCP/IP NT Protocol Adapter for Linux: Version 11.2.0.2.0 - Production
  Time: 19-JAN-2013 12:46:53
  Tracing not turned on.
  Tns error struct:
    ns main err code: 12535
TNS-12535: TNS:operation timed out
    ns secondary err code: 12606
    nt main err code: 0
    nt secondary err code: 0
    nt OS err code: 0
  Client address: (ADDRESS=(PROTOCOL=tcp)(HOST=10.64.108.62)(PORT=58380))
WARNING: inbound connection timed out (ORA-3136)

根据上篇文章介绍，有三种主要因素会导致这个warning的出现：

1. Server gets a connection request from a malicious 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. The server receives a valid client connection request but the client takes a long time to authenticate more than the default 60 seconds.
3. The DB server is heavily loaded due to which it cannot finish the client logon within the timeout specified.

第1种可以通过sqlnet.log文件确定，第3种可以通过查看db server的load来确定。

下面再现第2种可能：

通过oracle 11gr2 client 连接db，然后故意输入错误的账号密码，等待60秒钟，检查alert日志文件就可以看到这种warning了。

C:\Users\mdu>sqlplus system@chnpelt1-vip

SQL*Plus: Release 11.2.0.1.0 Production on 星期六 1月 19 13:58:11 2013

Copyright (c) 1982, 2010, Oracle.  All rights reserved.

输入口令:

连接到:
Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management,
Data Mining and Real Application Testing options

SQL> conn elitee@chnpelt1-vip   ###输入错误的用户名及密码
输入口令:
ERROR:
ORA-01017: invalid username/password; logon denied   

警告: 您不再连接到 ORACLE。
SQL>   ####此session等待60秒钟不再做任何操作

 

CHNPELT1@shaplora01$ tail -20 alert_CHNPELT1.log
***********************************************************************

Fatal NI connect error 12170.

  VERSION INFORMATION:
        TNS for Linux: Version 11.2.0.2.0 - Production
        Oracle Bequeath NT Protocol Adapter for Linux: Version 11.2.0.2.0 - Production
        TCP/IP NT Protocol Adapter for Linux: Version 11.2.0.2.0 - Production
  Time: 19-JAN-2013 13:59:41
  Tracing not turned on.
  Tns error struct:
    ns main err code: 12535
TNS-12535: TNS:operation timed out
    ns secondary err code: 12606
    nt main err code: 0
    nt secondary err code: 0
    nt OS err code: 0
  Client address: (ADDRESS=(PROTOCOL=tcp)(HOST=10.64.108.62)(PORT=60809))
WARNING: inbound connection timed out (ORA-3136)

我们发现，已经再现成功了。

为什么要等待60秒钟呢？

因为在sqlnet.ora文件中有一个默认的参数SQLNET.INBOUND_CONNECT_TIMEOUT来控制这个时间，如果没有显式的指定此参数，那么默认就是60秒钟。

如果不想在alert日志中收到这样的报错，可以设置SQLNET.INBOUND_CONNECT_TIMEOUT=0.

下面是从网上搜索的关于SQLNET.INBOUND_CONNECT_TIMEOUT的介绍：

Question:  What is the "sqlnet.inbound_connect_timeout" parameter and how do I use sqlnet.inbound_connect_timeout for logging off idle sessions?

Answer:  The sqlnet.inbound_connect_timeout parameter is used to limit the time, set in seconds, for a client to connect with the database server and provide the required authentication information.