Oracle Linux has a default firewall in the name of package “iptables“. This firewall is enabled by default when installed .Without disabling or modifying it we could not access most of the  services provided by the Linux. For example, you may not be able to access your database and tomcat over the network.

We can disable the firewall by following the below procedure :

Firstly we need to install the iptables-services package by using following command –

sudo yum install iptables-services

Next disable the firewall by using following commands:

sudo service iptables start

sudo service iptables stop 

sudo chkconfig iptables off

To punch or block specific ports and for more information , refer to the following link.