问题原因:

Fatal NI connect error 12170.
  VERSION INFORMATION:
        TNS for Linux: Version 11.2.0.3.0 - Production
        Oracle Bequeath NT Protocol Adapter for Linux: Version 11.2.0.3.0 - Production
        TCP/IP NT Protocol Adapter for Linux: Version 11.2.0.3.0 - Production
  Time: 24-MAY-2017 18:40:22
  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=192.168.1.2)(PORT=44430))
WARNING: inbound connection timed out (ORA-3136)
Wed May 24 18:45:22 2017

解决方法:

[oracle@iZbp18v7ndmiqoklooj0l8Z admin]$ vim listener.ora
INBOUND_CONNECT_TIMEOUT_listener=0

[oracle@iZbp18v7ndmiqoklooj0l8Z admin]$ lsnrctl
LSNRCTL for Linux: Version 11.2.0.3.0 - Production on 24-MAY-2017 18:50:44
Copyright (c) 1991, 2011, Oracle.  All rights reserved.
Welcome to LSNRCTL, type "help" for information.
LSNRCTL> show inbound_connect_timeout
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=iZbp18v7ndmiqoklooj0l8Z)(PORT=1521)))
LISTENER parameter "inbound_connect_timeout" set to 0
The command completed successfully
LSNRCTL> exit
[oracle@iZbp18v7ndmiqoklooj0l8Z admin]

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TNS-12535: TNS:operation timed out (WARNING: inbound connection timed out (ORA-3136))