Start Iptables under Linux

Q. How do I start Iptables firewall under RHEL / Red Hat / CentOS / Fedora Linux from a shell prompt? How do I stop firewall?

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

Select Firewall configuration and just follow on screen instructions.

Once configuration is updated type the following 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