Installing Wireless Networks - SY0-601 CompTIA Security+ : 3.4

Before installing
a wireless network,

it's useful to know the
environment that you're

installing this equipment in.

So it's common to
perform a site survey,

where we're going to
get more information

about the wireless
infrastructure that may already

be in place.

There may be existing access
points in the same building

or location where you'll be
installing additional access

points, or there
may be access points

that are located nearby
that aren't necessarily

in your control.

This means we may need to work
around any frequencies that

are already in
use, or we may have

to put our access point in a
location that will minimize

the amount of interference.

And like most things
associated with technology,

these things tend
to change over time.

So you may want to perform
additional site surveys later

on down the line to make sure
that nothing has changed,

and that your wireless network
is performing optimally.

One way to visually see the
results of these site surveys

is to use a heat map.

There are a number
of tools that can

help you build these heat maps.

All you would need to do is
move around your building

and have this system
create, visually,

where your wireless
networks happen to be,

and where the largest
signal strengths might

be for that network.

There are a number
of software tools

that you could run on your
laptop or mobile device that

can give you information about
the local wireless network.

For example, you might want to
run a wireless survey tool that

can show you what type
of wireless signals

happen to be in your area.

You can also see what
frequencies are in use,

and what type of
potential interference

may already be on this network.

They might have built-in tools
in the existing access point

you're using that can provide
some of this information,

without needing
additional software

on a laptop or mobile device.

And some of these tools
are hardware-based,

that can provide you with
information about the spectrum

itself, so that you
can really start

to understand where
frequencies may be used,

and what devices are
using those frequencies.

Instead of just looking
at the frequency use,

you can also capture
information that's

being sent over that wireless
network with a wireless packet

analyzer.

Since this is
wireless, you simply

need to listen in to the
signals going around the room,

and capture anything
that you happen to hear.

But this means the
device you're using

can't be sending information
to that wireless network

at the same time.

That's because the
wireless receiver

would be overloaded by the
local wireless transmitter.

Many packet analyzers will
disable the sending function

from your device,
so that you can

hear all of the traffic
coming from the other devices

on the wireless network.

Sometimes, an operating
system or wireless analyzer

will only capture
information and display it

as ethernet frames.

But there's also a lot of
wireless specific information

being sent directly
from the access point

that you'll only be
able to see if you have

the appropriate
drivers or hardware

adapters that are supporting
the wireless capture function.

You can often use these
wireless packet analyzers

to view other information
about the wireless network,

such as the signal-to-noise
ratio, channel information,

utilization, and other details.

If you'd like to
try this yourself,

you can download Wireshark
from www.wireshark.org.

Install it onto a machine that
has a wireless adapter card,

and see if you can view some
of that wireless information

that's on your local network.

To avoid any type of
interference between access

points, we need to make
sure that access points that

are near each other are not
using the same frequencies.

If we look at the frequencies
available for 2.4 GHz,

you can see it's a very
small number of channels that

don't overlap with each other.

In the United States, channel
1, channel 6, and channel 11

have no interference
between each other.

So if you're running one
access point at channel 1,

and another at
channel 6, you'll want

to configure your third
access point use channel 11.

If you're using an access
point that supports 5 GHz,

you have many more
channels available.

Anything not in
red in this picture

are available in
the 5 GHz range,

giving you much more flexibility
for installing wireless access

points with those frequencies.

Here's a view of
two separate access

points that are configured
without using overlapping

channels.

One of these is using
channel 6, and the other

is using channel 11.

What you don't want to do,
is go into this network,

install a new access point,
configure for channel 8,

and you can see that that
new access point overlaps

and interferes with both of the
access points that were there

previously.

This is why it's so important to
perform your site surveys prior

to an installation, so that
you don't install an access

point on the wrong channel,
and create interference

for all of the other devices
on the wireless network.

If you're installing
a new access point,

you want to make sure that you
place it in the right location.

You want to have minimal overlap
with other access points.

You certainly don't want to
put the access points directly

next to each other.

But you also want to
maximize the coverage that's

being used in your environment.

This will also
minimize the number

of physical access
points you'll need,

which will ultimately
save you money.

You also want to make sure
the location you're installing

the access point is not going to
have other interference nearby.

You want to be sure you avoid
any electronic devices that

could create interference.

Make sure you avoid parts
of the building where

the signals could be absorbed.

And you want to be sure to
avoid other third-party wireless

networks that could potentially
cause additional interference.

And of course, you want
to get the access points

as close as possible to the
users that will need access

to this wireless network.

And you want to be sure that
you're putting the access

point in a place that doesn't
send that signal too far

outside of your
existing work area.

Here's a building
layout that we might

want to use to
install access points.

And we'll place access
points around the building

in a way that just barely
overlap with each other.

We're also going to
make sure that we choose

different channels for
these access points

so nothing is conflicting
with each other.

You can see that
channel 1 does not

have any type of connection with
a channel 1 anywhere nearby.

Channel 6 and channel 11 are
configured in a similar way.

By separating the
channels in this way,

we can be assured that
we're not creating

any interference between
these access points,

and your network is going to
run as efficiently as possible.

If you've ever walked around
a large office building,

you'll start to notice there are
quite a few access points that

have been installed.

And of course, each one
of those access points

has to be managed.

Each one of those has its
own separate configuration.

And you have to make sure that
you keep all of those devices

up to date with the
latest software.

To be able to do this,
we need some type

of centralized
management device.

And that would be our
wireless controller.

This allows us to
configure, update,

and maintain all of
the access points

that we have in
our infrastructure.

It's very common to connect
to these wireless controllers

from our desk using a
browser configuration,

so we'll often have
HTTPS to provide

encrypted communication
between our browser

and the wireless controller.

And if we step away
from this configuration,

there's usually a timeout period
where if no input goes by,

there will be an
automatic log out

from the wireless controller.

On the access points
themselves, we

want to be sure
that we are using

strong passwords, or
some other type of very

strong authentication method.

And we'll use our
wireless controller

to make sure that
all of those devices

are always updated to
the latest firmware.