How do I start Iptables firewall under RHEL / Red Hat / CentOS / Fedora Linux from a shell prompt? How do I stop firewall? How do I start or restart firewall on a bash shell?

First, you need to configure firewall rules by editing a text file located at /etc/sysconfig/iptables on RHEL/CentOS/Fedora Linux. You can also use setup command to configure firewall. Just type the following command as root user:

# setup

Select Firewall configuration and just follow on screen instructions.

Once configuration is updated type the following service command at a shell prompt:

To start firewall from a shell enter:

# chkconfig iptables on
# service iptables start

To stop firewall, enter:

# service iptables stop

To restart firewall, enter:

# service iptables restart