title: I can't connect to oracle database from the internet. Only locally
body: <p>the subject speaks what I have.
  Machine which has oracle database instance installed is located in the internal network and has access to the internet via router device.
  I set up the port mapping (1521->1521) on the router to this machine. But
  when I try to connect with sqldeveloper on the host machine with oracle database then the connection is ok. But when I tried make the connection on the remote machine it sees that port (1521) is closed.
  Further, I show you my status of TNS.</p>
  
  <pre><code>C:\Windows\system32&gt;lsnrctl status
  
  LSNRCTL for 64-bit Windows: Version 12.1.0.2.0 - Production on 19-JAN-2017 04:29:30
  
  Copyright (c) 1991, 2014, Oracle.  All rights reserved.
  
  Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=onoffline.ru)(PORT=1521)))
  STATUS of the LISTENER
  ------------------------
  Alias                     LISTENER
  Version                   TNSLSNR for 64-bit Windows: Version 12.1.0.2.0 - Production
  Start Date                19-JAN-2017 04:21:23
  Uptime                    0 days 0 hr. 8 min. 8 sec
  Trace Level               off
  Security                  ON: Local OS Authentication
  SNMP                      OFF
  Listener Parameter File       C:\app\Igor\product\12.1.0\dbhome_1\network\admin\listener.ora
  Listener Log File         C:\app\Igor\diag\tnslsnr\DESKTOP-LHFQ4BV\listener\alert\log.xml
  Listening Endpoints Summary...
    (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1521)))
    (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)    (PIPENAME=\\.\pipe\EXTPROC1521ipc)))
    (DESCRIPTION=(ADDRESS=(PROTOCOL=tcps)(HOST=DESKTOP-LHFQ4BV)    (PORT=5500))(Security=    (my_wallet_directory=C:\APP\IGOR\admin\orcl\xdb_wallet))    (Presentation=HTTP)(Session=RAW))
  Services Summary...
  Service "CLRExtProc" has 1 instance(s).
    Instance "CLRExtProc", status UNKNOWN, has 1 handler(s) for this service...
  Service "orcl" has 1 instance(s).
    Instance "orcl", status READY, has 1 handler(s) for this service...
  Service "orclXDB" has 1 instance(s).
    Instance "orcl", status READY, has 1 handler(s) for this service...
  Service "pdborcl" has 1 instance(s).
    Instance "orcl", status READY, has 1 handler(s) for this service...
  The command completed successfully
  </code></pre>
  
  <p>I noticed that I close port forwarding then telnet waits too long and aborts. But When I open port forwarding for 1521 port that connection is refused immediately.</p>