[oracle@localhost admin]$ cat listener.ora
# listener.ora Network Configuration File: /u01/app/oracle/product/11.2.0/db_1/network/admin/listener.ora
# Generated by Oracle configuration tools.

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost.localdomain)(PORT = 1521))
    )
  )

ADR_BASE_LISTENER = /u01/app/oracle

[oracle@localhost admin]$ cat sqlnet.ora
# sqlnet.ora Network Configuration File: /u01/app/oracle/product/11.2.0/db_1/network/admin/sqlnet.ora
# Generated by Oracle configuration tools.

NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT)

ADR_BASE = /u01/app/oracle

[oracle@localhost admin]$ cat tnsnames.ora
# tnsnames.ora Network Configuration File: /u01/app/oracle/product/11.2.0/db_1/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.

DB11GR2 =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost.localdomain)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = DB11gR2)
    )
  )

[oracle@localhost admin]$ lsnrctl status DB11gR2

LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 30-SEP-2013 09:28:49

Copyright (c) 1991, 2009, Oracle.  All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost.localdomain)(PORT=1521))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=DB11gR2)))
TNS-12541: TNS:no listener
 TNS-12560: TNS:protocol adapter error
  TNS-00511: No listener
   Linux Error: 111: Connection refused

Failed to Connect

Firefox can't establish a connection to the server at localhost.localdomain:1158.
Though the site seems valid, the browser was unable to establish a connection.

    * Could the site be temporarily unavailable? Try again later.
    * Are you unable to browse other sites?  Check the computer's network connection.
    * Is your computer or network protected by a firewall or proxy? Incorrect settings can interfere with Web browsing.

[oracle@localhost admin]$ lsnrctl start

LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 30-SEP-2013 09:51:09

Copyright (c) 1991, 2009, Oracle.  All rights reserved.

Starting /u01/app/oracle/product/11.2.0/db_1/bin/tnslsnr: please wait...

TNSLSNR for Linux: Version 11.2.0.1.0 - Production
Log messages written to /u01/app/oracle/diag/tnslsnr/localhost/listener/alert/log.xml
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=localhost.localdomain)(PORT=1521)))

Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 11.2.0.1.0 - Production
Start Date                30-SEP-2013 09:51:09
Uptime                    0 days 0 hr. 0 min. 0 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Log File         /u01/app/oracle/diag/tnslsnr/localhost/listener/alert/log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=localhost.localdomain)(PORT=1521)))
The listener supports no services
The command completed successfully

[oracle@localhost admin]$ lsnrctl status

LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 30-SEP-2013 09:51:55

Copyright (c) 1991, 2009, Oracle.  All rights reserved.

Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 11.2.0.1.0 - Production
Start Date                30-SEP-2013 09:51:09
Uptime                    0 days 0 hr. 0 min. 45 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Log File         /u01/app/oracle/diag/tnslsnr/localhost/listener/alert/log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=localhost.localdomain)(PORT=1521)))
The listener supports no services
The command completed successfully

[oracle@localhost ~]$ lsnrctl service

LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 30-SEP-2013 10:07:52

Copyright (c) 1991, 2009, Oracle.  All rights reserved.

Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
Services Summary...
Service "DB11gR2" has 1 instance(s).
  Instance "DB11gR2", status READY, has 1 handler(s) for this service...
    Handler(s):
      "DEDICATED" established:178 refused:0 state:ready
         LOCAL SERVER
Service "DB11gR2XDB" has 1 instance(s).
  Instance "DB11gR2", status READY, has 1 handler(s) for this service...
    Handler(s):
      "D000" established:0 refused:0 current:0 max:1022 state:ready
         DISPATCHER <machine: localhost.localdomain, pid: 9014>
         (ADDRESS=(PROTOCOL=tcp)(HOST=localhost.localdomain)(PORT=26728))
The command completed successfully

[oracle@localhost ~]$ emctl start dbconsole
Oracle Enterprise Manager 11g Database Control Release 11.2.0.1.0
Copyright (c) 1996, 2009 Oracle Corporation.  All rights reserved.
https://localhost.localdomain:1158/em/console/aboutApplication
Starting Oracle Enterprise Manager 11g Database Control ......... started.
------------------------------------------------------------------
Logs are generated in directory /u01/app/oracle/product/11.2.0/db_1/localhost.localdomain_DB11gR2/sysman/log

[oracle@localhost ~]$ emctl status dbconsole
Oracle Enterprise Manager 11g Database Control Release 11.2.0.1.0
Copyright (c) 1996, 2009 Oracle Corporation.  All rights reserved.
https://localhost.localdomain:1158/em/console/aboutApplication
Oracle Enterprise Manager 11g is running.
------------------------------------------------------------------
Logs are generated in directory /u01/app/oracle/product/11.2.0/db_1/localhost.localdomain_DB11gR2/sysman/log