title: The listener supports no services - connection closed
body: <p>Trying to configure a dblink I damaged the oracle listener in a SUSE with db Oracle, I undone the changes made in the files listener.ora and tnsnames.ora but it did not work, then I rebooted the computer and used lsnrctl status</p>
  
  <pre><code>Connecting to (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP) (HOST = 192.168.3.250) (PORT = 1521)))
  TNS-12541: TNS: no listener
   TNS-12560: TNS: protocol adapter error
    TNS-00511: No listener
     Linux Error: 111: Connection refused
  Connecting to (DESCRIPTION = (ADDRESS = (PROTOCOL = IPC) (KEY = EXTPROC1521)))
  TNS-12541: TNS: no listener
   TNS-12560: TNS: protocol adapter error
    TNS-00511: No listener
     Linux Error: 111: Connection refused
  </code></pre>
  
  <p>I understand that if I left everything as it was, LISTENER should have started automatically and without problems.</p>
  
  <p>Now I used $ ORACLE_HOME / bin / lsnrctl start LISTENER</p>
  
  <pre><code>STATUS of the LISTENER
  ------------------------
  Alias ​​LISTENER
  Version TNSLSNR for Linux: Version 11.2.0.2.0 - Production
  Start Date 07-JAN-2019 20:35:42
  Uptime 0 days 0 hr. 0 min. 0 sec
  Trace Level off
  Security ON: Local OS Authentication
  SNMP OFF
  Listener Parameter File /opt/oracle/product/11gR2/db/network/admin/listener.ora
  Listener Log File /opt/oracle/diag/tnslsnr/srvbdlnx/listener/alert/log.xml
  Listening Endpoints Summary ...
    (DESCRIPTION = (ADDRESS = (PROTOCOL = tcp) (HOST = 192.168.3.250) (PORT = 1521)))
    (DESCRIPTION = (ADDRESS = (PROTOCOL = ipc) (KEY = EXTPROC1521)))
  The listener supports no services
  The command completed successfully
  </code></pre>
  
  <p>Then I restarted LISTENER and apparently is listening:</p>
  
  <pre><code>Listening Endpoints Summary ...
    (DESCRIPTION = (ADDRESS = (PROTOCOL = tcp) (HOST = 192.168.3.250) (PORT = 1521)))
    (DESCRIPTION = (ADDRESS = (PROTOCOL = ipc) (KEY = EXTPROC1521)))
  Services Summary ...
  Service "app" has 1 instance (s).
    Instance "app", status READY, has 1 handler (s) for this service ...
  Service "appXDB" has 1 instance (s).
    Instance "app", status READY, has 1 handler (s) for this service ...
  The command completed successfully
  </code></pre>
  
  <p>But when I try to log in remotely in the application it does not work:</p>
  
  <pre><code>ORA-12537:TNS:connection closed
  </code></pre>
  
  <p>Modify the local_listener parameter in the db but it did not work.</p>
  
  <pre><code>alter system set local_listener='(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.3.250)(PORT=1521))';
  </code></pre>
  
  <p>The database is running because I can log in with the SYSTEM user in sqlplus in console.</p>
  
  <p>my listener.ora file:</p>
  
  <pre><code>LISTENER =
    (DESCRIPTION_LIST =
      (DESCRIPTION =
        (ADDRESS = (PROTOCOL = TCP) (HOST = 192.168.3.250) (PORT = 1521))
        (ADDRESS = (PROTOCOL = IPC) (KEY = EXTPROC1521))
      )
    )
  
  ADR_BASE_LISTENER = /opt/oracle
  </code></pre>
  
  <p>tnsnames.ora</p>
  
  <pre><code>APP =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP) (HOST = 192.168.3.250) (PORT = 1521))
      )
      (CONNECT_DATA =
        (SERVICE_NAME = app)
      )
    )
  </code></pre>
  
  <p>Is there something missing in the files that I modified? 
  What changes could have occurred due to the modifications I made to those files?
  What other commands can I use to see more errors?</p>
  
  <p>I am new, thanks in advance.</p>