title: IO Error: The Network Adapter could not establish the connection - with Oracle 11gR2. Connecting with SQL developer
body: <p>I have installed Oracle 11g ON a RedHat6 linux instance, by following all the steps mentioned in "<a href="http://technologylair.net/2013/08/oracle-11g-installation-linux/#comment-50" rel="noreferrer">http://technologylair.net/2013/08/oracle-11g-installation-linux/#comment-50</a>" I am trying to connect to the database from a remote machine using the sql developer. But always ending up with - "<code>IO Error: The Network Adapter could not establish the connection</code>".</p>
  
  <p>The parameters i am using are</p>
  
  <pre><code>Username: sys as sysdba 
  Password: &lt;oracle password&gt; 
  Hostname: IP address of the server on which Oracle SQL is installed. 
  Port: 1521 
  SID: testdb
  </code></pre>
  
  <p>I have also created a listener.ora file at location - "/oracle/product/11.2.0/db_1/network/admin", as it was not present before. Whose contents are -</p>
  
  <pre><code>SID_LIST_LISTENER =
    (SID_LIST =
      (SID_DESC =
        (SID_NAME = PLSExtProc)
        (ORACLE_HOME = /u01/oracle/product/11.2.0/db_1)
        (PROGRAM = extproc)
      )
    )
  
  LISTENER =
    (DESCRIPTION_LIST =
      (DESCRIPTION =
        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_TESTDB))
        (ADDRESS = (PROTOCOL = TCP)(HOST = 173.39.238.15)(PORT = 1521))
      )
    )
  
  DEFAULT_SERVICE_LISTENER = (TESTDB)
  </code></pre>
  
  <p>I have posted this question on dba.stackexchange too. but i need to get this resolved as soon as possible. and need help. Hence posting it here too.</p>
  
  <p>Can you please tell me what i might be doing wrong. </p>
  
  <p>Thanks.</p>
  
  <p><strong>EDIT</strong> the out put of "lsnrctl status"</p>
  
  <blockquote>
    <p>Connecting to
    (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC_FOR_TESTDB)))
    TNS-12541: TNS:no listener  TNS-12560: TNS:protocol adapter error<br>
    TNS-00511: No listener    Linux Error: 2: No such file or directory
    Connecting to
    (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=173.39.238.15)(PORT=1521)))
    TNS-12541: TNS:no listener  TNS-12560: TNS:protocol adapter error<br>
    TNS-00511: No listener    Linux Error: 111: Connection refused</p>
  </blockquote>