To connect to a box on your network that is running Oracle Database, you will first need to allow connections to Oracle through your firewall.
If you’re running CentOS, RHEL, Fedora or any other Linux variant that uses
iptables, use the following commands to create a firewall exception (Assuming you’re running your listener on port 1521 - check with
sudo lsnrctl status):
sudo iptables -I INPUT -p tcp --dport 1521 -j ACCEPT