This is the wiki with technical documentation of the networking code in IPFire 3.x.
At first of all, you should know that there is a "network" command that lets you control everything you need.
When the system boots up, all ethernet devices are scanned and automatically added to the network configuration.
They are called Ports and do only forward ethernet frames. They do not have any layer 3 protocol on them.
A zone is a network device which actually used by the applications and system. This is the place where IP addresses are configured and routing is done.
Configurations are a bunch of settings that get applied to zones. This could be for example an IPv4 address.
The man pages are available online as HTML documents. They are automatically exported and therefore always up to date.