Knowledge of assigned IP addresses to your devices.
There's many ways that you could take advantage of this.
In this video, we'll look at many ways
to use these IP addresses.
One common type of virtual private network, or VPN,
is one that uses SSL, or Secure Sockets Layer.
These SSL VPNs use a very common protocol, which is TCP/443.
This is the same protocol that we
use to communicate securely to web servers inside
of our browser.
This means we can avoid a lot of problems with firewalls
by using this very common and well-used protocol.
SSL VPNs are commonly used for end user communication
so that you can have a secure tunnel between your device
and your corporate network.
And SSL VPN can also be relatively easy to install.
You would simply assign authentication credentials
to a user so they would use the same username
and password they always use to gain access to this SSL VPN.
You don't necessarily need to roll out digital certificates
to everybody's workstation or configure shared pass
phrases like you do with IPSec.
Many SSL VPN clients can run inside of a browser,
or they might already be built into your operating system.
You simply provide the username and password and the IP
address that you want to connect to,
and you've got an SSL VPN tunnel.
You often hear these SSL VPNs referred
to as client-to-site VPNs, or remote access VPNs,
because you can be anywhere remotely out in the world
and be able to communicate securely
back to your corporate network.
If you have your laptop at a hotel or a coffee shop
and you want to communicate back to corporate,
you simply start the SSL VPN software on your laptop,
and it creates this encrypted tunnel back
to your VPN concentrator at your corporate facility.
This means if anyone was to capture
any of this traffic between your workstation and this VPN
concentrator, all they would see is encrypted communication.
Your VPN concentrator is responsible for then decrypting
that information and sending it into the corporate network.
When this information is sent back to your remote laptop,
it is encrypted by the VPN concentrator
and sent over that encrypted tunnel
and then decrypted by your laptop.
This means that no matter where you are in the world,
you know you can start your SSL VPN software
and have this encrypted secure tunnel back
to your corporate network.
A LAN is a local area network.
We define this as a group of devices
that happen to share the same broadcast domain.
For example, we have two switches on our network.
The switch on the left and all of the devices connected
to that switch are one broadcast domain.
And we have a switch on the right,
and there's devices connected to that switch.
Those devices are on a different broadcast domain.
We often maintain the separation between different local area
networks for security reasons and to maintain
the efficiency of the network.
But this also means that we would
have to have a separate switch every time
we wanted to have a separate broadcast domain.
To simplify this, we create a virtual local area
network or a VLAN, which means that we
can have a single switch.
But inside the switch, we are logically
separating these different networks into two pieces.
We still have the red network on the left,
and all of the devices on the red network
can only see the other devices on the red network.
And then we have the blue broadcast domain network
on the right side.
And again, only the blue devices can communicate back and forth
to other blue devices.
This greatly simplifies the administration
and the cost of having multiple switches on our network.
Instead, we can configure a single switch
to act and operate as if it's multiple switches.
For example, here's a single switch
where three separate VLANs have been configured.
We have the red VLAN, which is VLAN 1.
That's for the gate room.
We have VLAN 2.
That's the blue one that has the dialing room.
And then the green VLAN is VLAN 3 for the infirmary.
So all of the devices that are connected to the red ports
can communicate to each other on VLAN 1.
The devices on the blue network can communicate to each other
and the devices on the green network
can communicate to each other.
And none of the devices on these separate networks
are able to communicate across that VLAN separation.
That allows you to maintain the security and the efficiency
of the network while minimizing the number of switches
that you need to have running at any particular time.
It's estimated that there are over 20 billion devices
connected to the internet.
But we know that IP version 4 can only support just over 4
billion addresses.
This also means that the entire address space for IPv4
has been easily exhausted at this point.
But we still have a requirement to connect
these 20 billion devices that are on the internet.
The way we do that is by using Network Address
Translation, or NAT.
This is just one of the ways that we can
take advantage of using NAT.
But it's one of the most common ways
so that you can have many devices
on the inside of your network all
translating out to a single device on the public internet
side.
Network Address Translation literally
changes, or translates, one IP address to another.
For example, we have an internal network,
where Vala has her laptop.
And she wants to communicate out on the public internet
to my website, professormesser.com.
When she sends traffic from her workstation,
the source IP will be that of her laptop,
which is 10.10.20.50.
And she wants to communicate to my web server,
which is 104.20.19.63.
When she sends this information to her router,
her router has been configured to perform Network Address
Translation.
And it changes the source IP from her internal address
to the external address on the public internet
and then sends that information to my web server.
When my web server wants to respond back,
it simply reverses those IP addresses, has the source
IP as my web server, and the destination IP as the public IP
address on the internet.
When it's received by that router,
the router translates it again back
to Vala's internal IP address and sends that information down
to her laptop.
This Network Address Translation happens
for all of the devices on your internal network.
So you can have hundreds or even thousands
of devices on your internal network
all being translated to one single IP
address on the internet.