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

Installing a wireless network can be an involved process. In this video, you’ll learn about site surveys, channel selection, access point placement, and more.

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 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.