Issue

How to disable firewall in Oracle Linux 7.5? 

Introduction to firewall in Oracle Linux 7.5

Unlike previous Oracle Linux releases which uses 'iptables' command, the newer Oracle Linux 7.x release uses 'firewalld' command to manage the firewall.

Firewalld uses zones and services in comparison to iptables that make use of chains and rules.

Firewalld is a dynamically controlled service and lets you change the configuration of firewall even when it is running.

Solution

Disable the Firewall
To disable firewalld service run the following command from 'root' user.

systemctl disable firewalld 

To enable the firewall service run the following command from 'root' user:

systemctl enable firewalld 

To start the firewall service run the following command from the 'root' user:

systemctl start firewalld 

To stop the firewall service run the following command from the 'root' user:

systemctl stop firewalld 

+ Oracle Linux 7.5