Check and open ports in CentOS / Fedora / Redhat


If you want to open or close a port for a Linux firewall you have to edit the rules in the iptables configuration. By default iptables firewall stores its configuration at /etc/sysconfig/iptables file. You need to edit this file and add rules to open port.

Here are the steps to open the port XY using the default visual editor vi:

Open port XY

Open flle /etc/sysconfig/iptables:

vi /etc/sysconfig/iptables

Append rule as follows:

-A RH-Firewall-1-INPUT -m state –state NEW -m tcp -p tcp –dport XY -j ACCEPT

Save and close the file. Restart iptables:

/etc/init.d/iptables restart

Verify that port is open

Run following command:

netstat -tulpn | less

Make sure iptables is allowing port connections:

iptables -L -n