-: Wireless access points.
In addition to selecting the right encryption,
it's also important to select
the right placement and configuration
of your wireless access points
in order for you to achieve
a good security posture.
Most small office, home office wireless systems
rely on a single-point to multi-point setup.
This relies on having a single access point
that services all of the wireless clients.
For example, on this floor plan,
you can see the strongest signal is the red spot,
that's centered around
a single wireless access point,
and all of the other office cubicles
are connecting back into it.
In this next example,
you can see a multi-point to multi-point system.
This has multiple access points
that are going to be used to
provide the wireless network services in an ESS,
or extended service set configuration.
They're all going to work together
to provide one common network
that's supported by these multiple access points.
Now, in both of the previous examples,
the wireless access points are using
an omnidirectional antenna.
This means that the access point is going to
radiate out its signal equally
in every single direction.
Now, this can be good
from a coverage perspective,
but it also is dangerous.
You may want to control
which direction the signal is actually radiated,
and if you do,
you can do that using a bidirectional
or a unidirectional antenna.
For example, in a unidirectional antenna,
all of the transmission power is going to be
focused at a single direction.
This allows you to choose
which areas receive the signals,
and which ones don't.
So, in this example,
we're using a left-side focused antenna,
and it only transmits out to
computers on that side of the building,
while the computers on the right
are going to remain in an uncovered area
and not get any signal.
Now, we've talked about this
back in our Network+ curriculum, as well,
but from an operational standpoint,
we're trying to
increase the coverage to all areas
when we're talking Network+.
Now, from a security perspective, though,
we may actually want to limit
the area of coverage.
Let's look at our heat map once more.
Here, you can see
an extended service set configuration
with two access points.
Each of those access points
has omnidirectional antennas.
This is giving us good,
adequate coverage around the office base,
as you can see inside the floor plan.
So, our network technician for Network+
did a good job here.
Now, for this office,
each cubicle also has
a wired physical connection,
but the access point there is just to
provide the employees access
while they're sitting at
those conference tables in the middle,
or if they're walking around
using their cellphones.
Now, all of this is great,
and there's good coverage,
meaning that it's meeting our operational needs.
But, you'll also notice
that orange and yellow area,
which represents the medium
and lower-signal areas that are radiating
outside the walls of the building.
If I was an attacker,
I could park my car in that yellow area,
because that's part of my parking lot,
and I can pull up my laptop
and connect to the wireless network.
So, this becomes a security risk
for the organization,
and as a security analyst,
it's our job to figure out
exactly where the signal is,
where it's radiating to,
and prevent it from radiating
outside of our building.
Another area is if you're in a strip mall,
or you have offices right next door to you.
If it's radiating through the wall,
people in that office
can gain access to your network.
Again, this is something you need to worry about
as a security practitioner.
So, to prevent this bleed over,
you're going to use directional antennas
to emanate only out into controlled patterns.
You can also turn down
the power level that you're radiating at
to minimize the distance being covered
by your wireless signal,
and keep it inside your building.
Also, it's important to understand
what type of wireless access point
you're actually using.
Is it a B, a G,
an N, or an AC?
Because each of those uses a different frequency
that's being transmitted.
If you're using wireless B or G,
or some early versions of wireless N,
then you're transmitting at 2.4 gigahertz.
If you're using wireless A, AC,
or the newer wireless N devices,
you're transmitting at 5 gigahertz.
So, what does that really mean
when we talk about the frequency?
Well, if you have a 5-gigahertz frequency,
that means there's a shorter wavelength being used,
and because of that shorter wavelength,
the signal is actually going to
travel a shorter distance,
so, if you've a smaller number,
2.4 gigahertz,
that gives you a longer wavelength,
which means it can travel further distances
before it breaks down.
2.4 gigahertz, therefore,
is more prone to leak through a wall
than a shorter 5-gigahertz signal
due to the way that radio frequencies
propagate across the air and across
the physical construction of the walls.
Another reason it's important
to understand what signals you're using
is to help you identify if
there's any signals that cause
interference in your area.
For example, you might be getting
bumped offline a lot,
and causing a denial of services condition
if someone is using 2.4 gigahertz
cellphones or cordless phones
in an area where you have
your 2.4 gigahertz network.
So, understanding your conditions
is going to be important to making sure that
your network is staying up and secure.
So, how do you determine
what signals are around your office
that may be causing jamming or interference?
Well, you can do this by
conducting a wireless site survey,
using a tool like Netstumbler,
or you can pull out a spectrum analyzer.
This will allow you to see
what frequencies are in use
and how strong they are
to see if they're having
an effect on your network.
Now, most wireless access points
do have some built-in security features
that you can configure, as well.
This includes things like a basic firewall
with stateful packet inspection,
MAC filtering,
different levels of encryption
that we've already talked about,
and the ability to disable your SSID broadcast.
Some more advanced wireless access points,
though, also feature access point isolation.
Access point isolation creates
a network segmentation between each client
that's connecting to the access point,
and it prevents them from communicating with
any other client
and only allows them direct access
to the network's resources or the Internet.
As you can see,
there are a lot of ways to help increase
the security of your wireless networks,
but I still recommend that
you avoid wireless, whenever possible.
In fact, when I built my house,
we had two CAT5E network jacks installed in
every single room of the house.
This means that we don't have any computers,
TV, or video game consoles
that are using a wireless network
inside the home.
But, I do still have a few wireless access points
in my home network,
because some devices don't have
a wired network capability.
You think about your tablets,
or your mobile phones,
or your Nintendo Switches, right?
These don't have a way to plug in
to the wired network,
so, they have to use wireless
to connect to the Internet.
Also, when my friends come over,
they want to be able to
connect to the wireless network
and get out to the Internet too.
Now, to make sure I keep
my home network secure, though,
I actually isolated off this wireless network
away from my main network,
and it only has access directly to the Internet.
This prevents anyone from
using that wireless network
as a back door method of
getting into my wired network.