The right address, the wrong shop
You type the right web address of your bank. The page looks perfect. But it is a copy, and it is not the bank.
You did nothing wrong. Something between you and the bank sent you to the wrong place.
Today you learn how, and why a free Wi-Fi in a cafe is a risk too.
By the end of this lesson
Note
I can explain how an attack on the domain name system redirects traffic, and why open Wi-Fi is risky.
Key words
| Word | What it means | Example |
|---|---|---|
| Network | Computers joined together so they can share data. | |
| Router | A device that passes traffic between networks. | |
| Malware | Harmful software. | |
| IP address | The number that names a computer on a network. | 10.0.0.5 |
| Domain name | The name people type for a website. | college.example |
| DNS | Domain name system: the service that turns a domain name into an IP address. | |
| DNS server | A computer that answers DNS questions. | |
| Redirection | Sending traffic to a different place than the one asked for. | |
| Pharming | Redirecting you to a fake website, even when you type the right address. | |
| Open Wi-Fi | A wireless network with no password, so anyone can join. | |
| Eavesdropping | Secretly listening to other people's traffic. | |
| VPN | Virtual private network: a private, scrambled tunnel across the internet. | |
| HTTPS | The secure kind of web link. The page and you talk in scrambled form. |
The cells students fill in are left blank in this preview.
Starter: what you already know
Have a go
Starter: what you already know
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Cycle 1: DNS is a phone book
Computers find each other by IP address, a number. People prefer names.
The DNS is like a phone book. You ask for a domain name. The DNS server gives back the IP address.
You type college.example. DNS answers 10.0.0.5. Your browser then goes to 10.0.0.5.
Try it: a phone book in code
book = {"college.example": "10.0.0.5", "shop.example": "10.0.0.9"}
name = "college.example"
print(name, "is at", book[name])
# An attacker changes one line in the book:
book["college.example"] = "66.6.6.6"
print(name, "is now at", book[name])
A DNS attack and redirection
In a DNS attack, the attacker changes the answers. The name stays right, but the number is wrong.
Your browser goes to the attacker's computer. This is redirection of traffic. When the page is a fake, it is called pharming.
Impact: stolen logins and card details, and malware downloads.
Check: DNS
Have a go
Check: DNS
4 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.