Linux open ports Allow network connectivity

Linux open 1521 port allows network connection to Oracle Listener

Symptoms:
1. TCP/IP connectivity is on-the-pass. You can test with the ping command.

2. The Oracle listener on the server has been started.
Lsnrctl Status View Listener state
Lsnrctl Start Oracle Listener

3. The error message that the client gets is usually: Ora-12170:tns: Connection timed out

At this point, we can basically be sure that the server is not open 1521 port (assuming you use the default settings)

Workaround:

1. If you are in a LAN environment, configure a firewall. Then you can turn off the Linux firewall.
sudo service iptables stop

2. Edit Iptables, open 1521 port:

sudo vi/etc/sysconfig/iptables
-A input-p tcp-m state--state new-m TCP--dport 1521-j ACCEPT
: Wq
Restarting the firewall
sudo service iptables restart
Save the configuration so that it still works after the Linux reboot
sudo service iptables Save

To view firewall rules:
sudo iptables-l-n

Linux open ports Allow network connectivity