- On lesson 14.3,
we're gonna continue talking about wireless,
but this time from a wireless design perspective.
Now, wireless network design takes
into consideration geographic location,
radio frequency, that's the RF signal strength,
building and site construction, what it's made of,
the number of users, the type of use, and equipment options.
Now, a pre-planned wireless design is really necessary,
really crucial for creating a robust, reliable,
and secure wireless networks
that enable connectivity, mobility, productivity,
and enhanced user experience.
You know, it wasn't all that many years ago
where corporate organizations really frowned on wireless,
that they didn't wanna have wireless,
they didn't feel like it was secure, you know,
maybe they instituted wireless in the break room
or maybe we had a segmented wireless network for visitors.
But now wireless is really ubiquitous
and our users expect when they connect
to a wireless network, it is going to work,
you know, hands down, no questions asked.
So let's talk about how we make that happen
with a good network design.
A starting place is doing a wireless site survey.
A wireless site survey allows network engineers
to proactively identify areas
of radio frequency coverage and the equipment necessary
to deliver the required signal at a given location.
Now, the objective of doing a wireless site survey is
to avoid common wireless network design problems
like dead spots, or coverage holds,
excessive interference, incorrect type,
and number of access points,
and just in general, right, wasted time and money.
So here are some site survey considerations
when a site survey's being done: location, use, users,
device, performance, building, infrastructure,
and your security requirements.
So location is all about the size and the complexity
of the physical location,
at where is the location actually sited?
Is it near an airport, you know?
Is it near an industrial setting?
Where is it?
And then use is the intended use to determine the number
of access points that will be needed.
Users is the number of anticipated users
as well as the number
of devices we can anticipate each user will have.
The device is what type of devices are we gonna have
and device specific requirements.
Are we gonna have laptops?
Are we gonna have tablets?
Are we gonna have smartphones?
Performance is our speed and performance expectation.
The building is the age and the construction materials
and what impact that will have on signal strength.
The infrastructures.
What do we have for space and equipment availability?
So for example,
do we have ethernet ports to connect our access points to?
Do we have wiring closets?
Do we have conduits
that we could run wires to our access points?
And then of course, our security requirements.
So what are our specific security considerations
and requirements?
These are all things we're gonna talk
about during a site survey.
Now, a predictive site survey uses software
to model the environment.
And typically what happens in a predictive site survey
is building floor plans are just loaded
into this really cool, predictive site survey software
to develop a wireless network design.
Now, the predictive software will just take a lot
of things into account, right?
They'll account for building materials, square footage,
number of end users, type of materials,
the antenna models you're gonna use
on your access points, and other variables
to provide a really reliable predictive wireless plan
for your site or your facility.
So we keep mentioning access points,
so let's talk a little bit more about them.
An access point, a wireless access point,
sometimes called a WAP, sometimes called an AP,
acts as a central transmitter
and receiver of wireless signals.
Now, an access point can bridge wired
and wireless IP traffic.
So we call it a bridge, because we know
that a bridge is what connects two dissimilar media,
and wired and wireless is dissimilar media.
And there's a couple
of different antennas that we might put on our access point.
An omnidirectional antenna radiates transmissions out
and receives transmissions in from all directions.
So 360 degrees.
Now that's generally used inside a building.
A directional antenna is used to focus a signal
in a specific direction,
and that's generally used to connect buildings.
And then we can run in a Wi-Fi heat map,
which is a visual representation
of wireless signals' coverage and strength.
There's some really awesome programs out there
that you can use to create these wireless heat maps
once your access points are all in place.
So what's a heat map gonna show you?
Signal strength, signal to noise ratio,
channel overlap, capacity, what you have, our access points,
associated access points, and a data rate.
So signal strength being the signal strength
of the access points.
The signal to noise ratio being the ratio
of signal strength relative to noise,
general noise in the environment.
A channel overlap is the number
of access points that overlap
on a single channel in a given area,
we may not wanna have that overlap.
Capacity determines
if the network meets the capacity requirements.
Access points is the number of audible access points,
ones that are actually broadcasting out there
that we can hear and see.
The associated AP, so it predicts,
which clients are gonna associate with which access points.
And the data rate.
It can predict potential client access point data rates.
So how do we know that a wireless access point is out there
and available to connect to?
Well, a wireless access point is going
to have what's known as an SSID.
A set service identifier,
which is a code that identifies that wireless access point
and all wireless devices that wanna communicate
on a network must have their SSID set
to the same value as the wireless access point SSID
to establish connectivity.
Now, by default,
the access point broadcasts its SSID every few seconds.
Now that's good, because our devices can discover it
but it can be bad, because our attackers
or our adversaries can also discover it.
So that broadcast can be stopped,
so that an attacker can't automatically discover the SSID.
However, because the SSID is included
in the beacon of every wireless frame, it is fairly easy
for a hacker equipped with sniffing equipment
to discover the value and to fraudulently join the network
even though the SSID had not been broadcast.
So how do our adversaries discover our Wi-Fi networks?
Well, they could do warstorming, using a drone
and Wi-Fi equipped device to detect Wi-Fi network.
Wardriving using a moving vehicle and Wi-Fi equipped device
to detect Wi-Fi networks.
Warwalking, which is walking around
with Wi-Fi equipped device to detect Wi-Fi networks.
And then sometimes what happens is,
folks will say, "Okay, we found a network.
I'm gonna let everybody else know it's available."
And that's what Warchalking is.
Warchalking is the drawing of symbols
in public places to advertise a Wi-Fi network.
Now, that could be a Wi-Fi network
that was generously left open
or one that is inadvertently left open,
but there's been very specific symbols.
And if you see a chalk on a sidewalk
or on the side of a building that's a drawing,
it's denoted by two half moons back to back,
you're being told right there.
There's an open wireless network that you can connect to.
So it may not be an adversarial thing per se,
but if you're connecting to their network,
well, maybe you get access into their network.
And at very least, right?
You are using up bandwidth that doesn't belong to you.
So we wanna make sure
that we do everything we can to secure our Wi-Fi networks.
So let's look
at some Wi-Fi network security hardening best practices.
Well, we've said this before,
well, I'm sure I'll say it again, right?
We wanna change the default login credentials, right?
The username and password for your wireless access points,
for your routers, and for all your other network devices.
And I know at this point you must be saying, "Really,
doesn't everybody just do it?"
But the answer is no.
There's so many devices out there right now
with the default credentials,
and those default credentials are easily accessible, right?
We just have to go out to the web
and do a little search for them.
We wanna have strong authentication and encryption.
So we wanna implement the latest Wi-Fi protocols.
Again, go to WPA3
and you will be at the latest and greatest.
You should be disabling remote management.
You wanna disable any remote management capabilities
on a wireless router or access point
unless absolutely necessary.
Again, we're trying to make the footprint
as small as possible.
We enable segmentation.
So we wanna segment our wireless network
into a virtual LAN or a VLAN.
We wanna disable the SSID broadcast.
Now, disabling the broadcast of the network's SSID
makes a network less visible to unauthorized users.
Now, a dedicated hacker will still find it,
so we need to know that.
So it's not a panacea.
It also is a little bit more difficult now
for regular users to find our network.
So there's more work involved
in letting them know how to connect,
but right, it does make the network less visible
to unauthorized users.
We can do MAC address filtering.
So if we know exactly what devices are gonna be connecting,
we can use MAC address filtering
to allow only authorized devices
to connect to the wireless network.
Remember, every network interface has a unique MAC address.
And lastly, and again, I've said this a lot
but I'm gonna keep saying it,
we wanna do regular firmware updates.
We wanna keep our wireless network devices
including routers and access points up-to-date
with the latest firmware updates.
All right, that my friends
brings us to a three second challenge.
Five challenge questions, three seconds each.
Let's do it.
Using software to model a Wi-Fi network.
What's that called?
1, 2, 3.
That's gonna be a predictive site survey.
Number two, visual representation
of wireless signal coverage and strength.
1, 2, 3.
That's gonna be a heat map.
Number three, the transmitter
and receiver of wireless signals.
1, 2, 3.
That's a wireless access point called a WAP or just an AP.
Number four, a code that indicates membership
with an access point.
1, 2, 3.
That's gonna be an SSID, right?
You become a member of that group.
And lastly, number five, using a drone
and Wi-Fi equipped device to detect Wi-Fi networks.
What's that called?
1, 2, 3.
And that is warstorming.
Okay, well, that brings us
to a security-in-action about warchalking.
You notice a chalk drawing
on the sidewalk outside of your network.
That's what it looks like.
It says SSID, whatever the SSID is and maybe bandwidth.
And you see these two open circles or half moons.
So what does it mean, right?
Is it just kind of a cool drawing or does it have meaning?
So I wanna know from you,
what does it mean and should you do anything about it?
Go ahead and put me on pause
while you think about the meaning.
Well, the drawing indicates,
there's an open wireless network broadcasting its SSID.
So the first question you should be asking yourself is,
is this my network, right?
Is this your network?
And if it isn't your network, well then the question is,
should we tell others that their network is wide open?
You wanna consult
with management regarding approaching another organization
with recommendations to secure that wireless network.
Now, if it is your network, right?
The question is, do you intend for it to be open?
Maybe you do.
Maybe you want it wide open for your customers.
If yes, be sure
to use strong remote access protocols, right?
You don't wanna let other people be able to come in
and remotely manage any of the APs on this network.
And if not, well,
one, you should disable the SSID broadcast
and you should change the name,
because now a lot of people know about that name.
And then you wanna determine,
how secure the wireless network needs to be
and implement appropriate controls, encryption,
MAC filtering, antenna placement, and signal strength.
A lot to do just from one little drawing,
but is it your network or somebody else's?
If it's yours, you've got a whole task list.
If it's somebody else's, well,
you have to decide how you're gonna approach them
and talk to them about it.
Doing that, definitely security-in-action.
There's your word cloud, quite a bit, again.
We've just done two lessons on wireless.
Make sure you're really comfortable and confident
with all of these concepts before moving on.
If not, go back to this lesson
and the previous lesson if you need to.
And when you're ready, head on over to the next lesson,
where for the next two lessons actually,
we're gonna be talking about mobile computing
and mobile connectivity.
See you there.