1. 1.5 Wired and Wireless Networks
In this unit you will cover…

2. Wireless and Encryption
In this lesson you will cover:
WIFI – What it is and how it works
Frequency and channels in WIFI communications
Encryption of wireless data

3. WiFi WiFi stands for Wireless Fidelity
WiFi is great – access computer networks without the need for all those pesky wires
As with everything in computing, wireless adheres to standards:
b, g, n or ac
These get progressively faster

4. Wifi Benefits and Drawbacks
Ethernet Benefits
Wifi Benefits and Drawbacks

5. How does it work? WiFi uses radio waves to send packets
It’s a lot less secure than wired Ethernet as all of your packets are being sent through the air rather than being contained in a cable
We can have issues with interference – for example Microwaves and Cordless phones use the same frequency as some WiFi networks

6. Popty Ping
In this picture, every time you microwave something, you’ll lose WiFi (or it will at least slow down) – don’t put your Access Point on a Microwave

7. Frequency and Channels
In radio transmission we use different frequencies – think about tuning an old fashioned FM radio…
Radio 1’s frequency is between 97 and 99mhz around the UK… tune your radio to the right frequency and you’ll hear Radio 1.

8. Frequencies and Channels

9. Frequencies and Channels
WiFi can use two different frequencies
2.4ghz and 5ghz
You can only listen to one radio station per frequency, but we can fit loads of WiFi networks in just two frequencies.
How?
The answer is channels. Because WiFi is digital, we can separate networks into different channels.

10. Frequencies and Channels
Bad news again though – there’s a limited number of channels AND some of them interfere with each other.
If your WiFi menu looks like this, there’ll probably be some interference between the networks – this will slow the network down

11. Frequencies and Channels
All of those networks might look something like this in a radio-wave view…
Looks a bit crowded, doesn’t it?

12. Frequencies and Channels
This diagram shows the 2.4ghz channels and how they overlap – notice there can only be 3 non-overlapping channels at any one time.
Fortunately, most Wireless Access Points automatically change channel depending on what other networks are present
This helps to reduce overlap and interference

13. Encryption Task
As wireless transmissions can be intercepted easily, we have to try and protect them
Find out:
What encryption is
How encryption works – some common examples (for WIFI)
How “public key” encryption works
The advantages and disadvantages of encryption
Key words – Asymmetric and symmetric

14. Encryption
When you join a wireless network you’re almost always asked to enter a password.
STOP
It‘s not a password – it’s a key. Totally different things!

15. Encryption
This man is catching your packets
That key isn’t just a way to stop people from stealing your internet connection; it ensures that all of your data that travels through the air is kept secure
Remember with WiFi, your data is literally just zooming through the air around you, it’s not locked up safely inside a cable. Anyone can just grab your packets from the air and look at them

16. Encryption
Encryption goes part of the way to protecting your data when it leaves your device (or heading back towards your device)
An encryption algorithm scrambles the data – but what if someone learnt how to unscramble it?
The answer is the key, the encryption algorithm uses the key to scramble the data; this means that it can only be unscrambled when the correct key is used

17. Encryption
Encryption doesn’t stop people from grabbing your packets from the air; they can still grab every single one
The difference is that the packets are absolutely useless to them, there’s no way they can make any sense of them without the correct algorithm and key
Encryption has become a hot topic in the news over the last few years…

18. Encryption Research either of the following:
FBI Apple Encryption Dispute
UK Government and Whatsapp Encryption
Produce a PowerPoint explaining (a slide for each of the following)
What it’s all about
What the government or FBI want changed
What would be good and bad about this
What would be the impact to normal people?