在$ORACLE_HOME/network/admin/sqlnet.ora文件添加如下跟踪参数：
TRACE_LEVEL_CLIENT=16
TRACE_FILE_CLIENT=CLIENT
TRACE_TIMESTAMP_CLIENT=ON
trace_directory_client=/home/oracle

[oracle@xuh ~]$ pwd
/home/oracle
[oracle@xuh ~]$ ls -l client*
-rw-r----- 1 oracle oinstall   130488 Jan 11 20:29 client_6966.trc
-rw-r----- 1 oracle oinstall    28096 Jan 11 20:51 client_7065.trc
-rw-r----- 1 oracle oinstall    28118 Jan 11 20:51 client_7068.trc
-rw-r----- 1 oracle oinstall 11956846 Jan 11 20:53 client_7098.trc
-rw-r----- 1 oracle oinstall   142884 Jan 11 20:57 client_7115.trc
-rw-r----- 1 oracle oinstall   142884 Jan 11 20:57 client_7120.trc
-rw-r----- 1 oracle oinstall   147248 Jan 11 21:20 client_7190.trc
[oracle@xuh admin]$ sqlplus system/oracle@mrhua   #客户端发起一次连接，就会产生一个跟踪文件
SQL*Plus: Release 10.2.0.5.0 - Production on Mon Jan 11 20:29:34 2016
Copyright (c) 1982, 2010, Oracle.  All Rights Reserved.
ERROR:
ORA-12537: TNS:connection closed
Enter user-name:
[oracle@xuh ~]$ more client_6966.trc
...skipping
[11-JAN-2016 20:29:17:908] niomapnserror: entry
[11-JAN-2016 20:29:17:908] niqme: entry
[11-JAN-2016 20:29:17:908] niqme: reporting NS-12537 error as ORA-12537
[11-JAN-2016 20:29:17:908] niqme: exit
[11-JAN-2016 20:29:17:908] niomapnserror: exit
[11-JAN-2016 20:29:17:908] niotns: Couldn't connect, returning 12537
[11-JAN-2016 20:29:17:909] niotns: exit
[11-JAN-2016 20:29:17:909] nigcui: entry
[11-JAN-2016 20:29:17:909] nigcui: Clr User Interrupt: hdl=1, prc=0x8c044618, ctx=0x5994870.
[11-JAN-2016 20:29:17:909] nigcui: exit (0)
[11-JAN-2016 20:29:17:909] nsbfrfl: entry
[11-JAN-2016 20:29:17:909] nsbrfr: entry
[11-JAN-2016 20:29:17:909] nsbrfr: nsbfs at 0x59abf20, data at 0x59abfd0.
[11-JAN-2016 20:29:17:909] nsbrfr: normal exit
[11-JAN-2016 20:29:17:909] nsbrfr: entry
[11-JAN-2016 20:29:17:909] nsbrfr: nsbfs at 0x59ac7f0, data at 0x59ac8a0.
[11-JAN-2016 20:29:17:909] nsbrfr: normal exit
[11-JAN-2016 20:29:17:909] nsbrfr: entry
[11-JAN-2016 20:29:17:909] nsbrfr: nsbfs at 0x59a80d0, data at 0x59a8180.
[11-JAN-2016 20:29:17:909] nsbrfr: normal exit
[11-JAN-2016 20:29:17:909] nsbfrfl: normal exit
[11-JAN-2016 20:29:17:909] nttdisc: entry
[11-JAN-2016 20:29:17:909] nttdisc: Closed socket 8
[11-JAN-2016 20:29:17:909] nttdisc: exit
[11-JAN-2016 20:29:17:909] nigtrm: Count in the NI global area is now 1
[11-JAN-2016 20:29:17:909] nigtrm: Count in the NL global area is now 1
[11-JAN-2016 20:29:19:235] nigini: entry
[11-JAN-2016 20:29:19:235] nigini: Count in the NL global area is now 2
[11-JAN-2016 20:29:19:235] nigini: Count in NI global area now: 2
[11-JAN-2016 20:29:19:235] nigini: exit
[11-JAN-2016 20:29:19:235] nigconcbs: entry
[11-JAN-2016 20:29:19:235] nigconcbs: exit
[11-JAN-2016 20:29:19:235] niotns: entry
[11-JAN-2016 20:29:19:235] niotns: niotns: setting up interrupt handler...
[11-JAN-2016 20:29:19:235] nigsui: entry
--More--(21%)

通过分析跟踪文件，以便我们更好的锁定问题、分析问题、解决问题！