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.

Here we are going to learn about how to open ports on CentOS using FirewallD.


# Create a symlink so the service can start with the server

systemctl enable firewalld

# Initialize the firewallD

systemctl start firewalld

# Add a new port in permanent mode to your firewall

firewall-cmd –permanent –add-port=100/tcp

# Reload

firewall-cmd –reload

# Finally, check the new port added with

firewall-cmd –list-ports