Firewall for Linux

To disable/enable the Linux firewall use the following command:

system-config-securitylevel-tui

For CentOS 6 and above

system-config-firewall-tui

If the package is not installed you can install it by using the following yum command.

yum install system-config-securitylevel-tui

To disable selinux on CentOS 6 which is not displayed in the above mentioned TUI edit
/etc/selinux/config

SELINUX=disabled

or

sed /s/SELINUX=enforcing/SELINUX=disabled/g /etc/selinux/config