A supermarket uses Wi-Fi to enable staff to check inventory levels and to perfor

Question

A supermarket uses Wi-Fi to enable staff to check inventory levels and to perform price checks. Staff has complained that the wireless scanners they use to check stock levels do not work reliably in some isles. The supermarket manager has contracted you to diagnose the wireless problems and correct them.

The supermarket is 60m by 40m.

Assume that the useful range of Wi-Fi within the warehouse will be 15m radius. The access points are organised into a grid with the following channel allocations:

Ch1

Ch6

Ch1

Ch6

Ch1

Ch6

You have determined that the channel allocations are not optimal, how would you improve upon the current channel allocations? (10 marks)

As you are reconfiguring the access points you notice that none of them currently have any security enabled. Is this a problem, and if so, what type of security would you recommend?

Ch1

Ch6

Ch1

Ch6

Ch1

Ch6

Explanation / Answer

Super market area is 60 * 40 mts = 2400 mts

Wifi range is 15 m radius....

The current channel allocation is

In the above approach we face more inter channel interference problem..

i.e., between ch1 and ch6

we reconfigure channels we may reduce these inter channel interference

The above configuration reduces the inter channell configuration....

Wifi Security issues:

Public Wi-Fi networks (for this, those with a Pre-Shared Key) are not much safer, if at all. While they may not have

the same intentions as retail stores, there is no level of assurance or legal obligation for them to secure your

device or data. Again, you have no way* to make sure no one can intercept and read and/or modify your data. You

should question why this network exists, especially if the connection is free. You are probably the "product" via

data mining (like retail stores above) or via advertising.

About Wi-Fi Attacks

War Driving

This is the act of driving around neighborhoods and areas to enumerate what wireless networks exist, what type of

encryption (if any) is used, password (if known), and any other pertinent information. This information may chalked

or painted to the street or side walk or posted to various websites. Some websites, like SkyHook ask their users

for this. Be cautious when you see various cars sitting outside your house for long periods of time (unless you live

near a Pokemon Gym or a Pokestop).

Cracking Attacks

Just like anything else using Passwords, there are desires and ways to crack those passwords to gain access.

Without password attacks, there would be no Have I Been Pwned and other similar sites. Very much like other

password attacks, there are the simplistic attacks (brute force) and the complex attacks. While brute force will

eventually work, there are methods to minimize the impact if compromised. These mitigating factors are mentioned

below in the Wi-Fi Security Tips. One tool, or rather a suite of tools, used to crack wi-fi (WEP, WPA1, and WPA2)

passwords is Aircrack-ng. It is the replacement for Airsnort. You will also need the airmon-ng, airodump-ng, and

aireplay-ng tools (hence the suite) as well as a wireless card set to to "Monitor Mode" (like promiscuous mode) to

steal the handshake file and replay handshake to get the file to crack. Once you have the file, you can use your

favorite password list (mine is a custom list with rockyou.txt as a base) to attempt to crack the key.

Denial of Service

A Denial of Service (DoS) attack is more of a nuisance than a true technical attack. Think of it as an extreme brute

force attack that overwhelms something, in this case, a Wi-Fi network or assets/nodes on it. My broad over

generalization of it being a nuisance vice technical is an exaggeration; sometimes the vectors of attack for a DoS

are very technical. Many technologies, namely web servers and websites, have DoS protective measures, as the

internet can connect to them if they are public facing.

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