Unlike the example configurations in The firewall scripts files, configuring a Linux Server to masquerade and forward traffic generally from the inside private network that has unregistered IP addresses
i.e. 192.168.1.0/24 to the outside network i.e. the Internet require a special setup of your kernel and of your firewall configuration scripts file. This kind
of setting is also known as a Gateway Server, a machine that serves as a gateway for internal traffic to external traffic. This configuration must only be set if you have the intentions and the needs for this
kind of service and it's for this reason that the configuration of the script file for the Gateway Server is in its own chapter.