If you are working with some services or ports that your application is using and if you are not receiving information from the server, probably it’s because your firewall is not running or doesn’t have the rules for the port you are using.
- Create a symlink so the service could start automatically at boot.
systemctl enable firewalld
- Start the firewalld.
systemctl start firewalld
- Add a new port in permanent mode to your firewall.
firewall-cmd --permanent --add-port=100/tcp
- Finally, check the new port added.