- [Instructor] You can turn any
ordinary computer into a router.
Here is what you need.
Hardware-wise, a second network interface card,
or NIC, is necessary.
In terms of software, you could be using
any Linux distribution.
Ubuntu is our choice.
If you're using a physical computer,
go ahead and plug in your second NIC and set it up.
A virtual machine, or VM, requires a virtual NIC.
Here is the big picture view.
Think of what a home router does.
It allows you to share a single external IP address
among multiple hosts in the same local area network, or LAN.
We call this feature network address translation, or NAT.
NAT also enables you to forward packets.
There could be two types of forwarding.
One is ingress forwarding, meaning forwarding packets
from outside your network into your network.
The other is egress, meaning forwarding packets
from within your network to the outside of your network.
This diagram shows our overall network architecture
we're working toward throughout this course.
In the previous lessons,
we set up our host firewall on a local host.
The rest of the architecture
yet to be completed is grayed out.
In this chapter, we'll configure
a second Ubuntu VM host as a router.
It has two network interface cards,
network interface card zero, or eth0,
and network interface card one, or eth1.
Between these two network interfaces
is where the forwarding is happening,
whether it's ingress forwarding or egress forwarding.
And behind the Ubuntu host as a router,
you can see an additional host connected
through a switch the is also connected
to the Ubuntu host routers NIC1 or eth1.
What I'm showing you here is precisely
how your home router works.
The only difference is that the entire computer,
namely Ubuntu host, is now dedicated as a router.