title: ORA-12154: TNS:could not resolve the connect identifier specified
body: <p>I am trying to connect to oracle 11g installed on Linux EL 5 and and getting the following error</p>
  
  <pre><code>SQL&gt; connect sys/password@ud06 as sysdba
  ERROR:
  ORA-12514: TNS:listener does not currently know of service requested in connect
  descriptor
  </code></pre>
  
  <p>my listener.ora under network/admin is as follows</p>
  
  <pre><code>LISTENER=
    (DESCRIPTION=
      (ADDRESS_LIST=
        (ADDRESS=(PROTOCOL=tcp)(HOST=ud06)(PORT=1521))
        (ADDRESS=(PROTOCOL=ipc)(KEY=extproc))))
  
  SID_LIST_LISTENER=
    (SID_LIST=
      (SID_DESC=
        (GLOBAL_DBNAME=orcl)
        (ORACLE_HOME=/home/oracle/app/oracle/product/11g)
        (SID_NAME=orcl))
      (SID_DESC=
        (SID_NAME=plsextproc)
        (ORACLE_HOME=/home/oracle/app/oracle/product/11g)
        (PROGRAM=extproc)))
  </code></pre>
  
  <p>MY tnsnames.ora is as follows</p>
  
  <pre><code>ORCL =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost.localdomain)(PORT = 1521))
      (CONNECT_DATA =
        (SERVER = DEDICATED)
        (SERVICE_NAME = orcl)
      )
    )
  
  EXTPROC_CONNECTION_DATA =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
      )
      (CONNECT_DATA =
        (SID = PLSExtProc)
        (PRESENTATION = RO)
      )
    )
  
  UD06=
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = ud06)(PORT = 1521))
      )
      (CONNECT_DATA =
        (SERVICE_NAME = orcl)
      )
    )
  </code></pre>
  
  <p>MY lsnrctl status shows as follows:</p>
  
  <pre><code>LSNRCTL&gt; status
  Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=ud06.us.server.com)(PORT=1521)))
  STATUS of the LISTENER
  ------------------------
  Alias                     LISTENER
  Version                   TNSLSNR for Linux: Version 11.2.0.1.0 - Production
  Start Date                17-FEB-2010 16:23:06
  Uptime                    0 days 0 hr. 12 min. 33 sec
  Trace Level               off
  Security                  ON: Local OS Authentication
  SNMP                      OFF
  Listener Parameter File   /home/oracle/app/oracle/product/11g/network/admin/listener.ora
  Listener Log File         /home/oracle/app/oracle/product/11g/log/diag/tnslsnr/ud06/listener/alert/log.xml
  Listening Endpoints Summary...
    (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=ud06.us.server.com)(PORT=1521)))
    (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=extproc)))
  Services Summary...
  Service "orcl" has 1 instance(s).
    Instance "orcl", status UNKNOWN, has 1 handler(s) for this service...
  Service "plsextproc" has 1 instance(s).
    Instance "plsextproc", status UNKNOWN, has 1 handler(s) for this service...
  The command completed successfully
  </code></pre>