Unit 5 - The Internet & Its Uses

The internet and the world wide web

Functions of a web browser:

• Storing bookmarks and favourites

Web browsers can bookmark pages of interest or importance to its users. If you visit a website very frequently, it could save you a lot of time to add this website to your bookmarked websites, so next time you want to visit that website you can simply click on the bookmark, rather than type in the URL.

• Recording user history

Whenever we visit a web page, this is added to the history feature of the web browser. The history feature keeps a chronological record of each site visited. 

• Allowing use of multiple tabs

Tabs allow the user to have multiple pages open in a single web browser window.

• Storing cookies (see next section about cookies)

• Providing navigation tools

The navigation tools include, forward button, backward button, reload, home, add tab, close tab.

• Providing an address bar

This is where we type in the URL of the web page we want to view. Without this feature, users would not be able to browse through a web page.

Accessing resources on the world wide web

You access a resource on the world wide web by typing the URL in the address bar of the web browser and pressing Enter or clicking on a link.

But what is the magic that happens when you press Enter or click a mouse button?

1. Find the IP address of the web server where the web page you want to visit lives on. Computers connected to the internet communicate each other using their IP address. All computers and devices connected to the internet have their own unique IP address. The web pages that you visit are all stored on web servers. These web servers have a unique IP address. So, when you typed in a URL, the internet does not know its meaning, it needs to find this URL's corresponding IP address. How to find it? 

Using the Domain Name Server (DNS). The DNS stores a list of domain names together with their corresponding IP addresses. So, when you pressed Enter, the first thing that the browser did was to ask the DNS for the IP address of your URL.

Note, there are many DNS servers, if the one your browser asked didn't have the IP address it was looking for, that DNS will redirect the request to another DNS.

2. Request the web page from the web server. Now that your browser has the IP address corresponding to the web server that stores the web page you want to visit, the web browser will send an HTTP request (remember the GET request code?) to the web server asking to send a copy of the web page.

3. Browser renders HTML into a web page. Once your browser receives the copy of the web page file (usually created using HTML) from the server, it translates the HTML and displays the web page on screen.

Cookies

Cookies are small text files that are stored on the user's computer system and are used by the web browser.

Cookies store, personal information (e.g. your name, address, phone number), preferred language, location, items in a shopping cart, login details.

There are two types of cookies:

• Session cookies

Session cookies are used to recognise users when they move from page to page within a website and to remember any information the user has entered. 

Session cookies are needed for e-commerce sites to remember items placed in a shopping cart, and for websites whose functionalities depend on the users' activities. These cookies store the user's input and track the user's movements within the website.

Session cookies are deleted once you close the browser, or log out of the particular website.

• Persistent cookies

They store data associated with a particular customer. These data is stored in small files on the hard disk of your computer system, and will be used whenever you browse the website associated with this cookie.

Cookies have an expiration date, so your data will be stored in the cookie until the cookie expires.

Digital currency

You may have heard of ‘Bitcoin’, ‘Ethereum’ or even ‘DogeCoin’. These are names of popular cryptocurrency, or digital currency.

Digital currency is a form of currency, like Euros or Dollars, that exists only in a digital format. The digital currency has no physical attributes, like a coin or bank note, but instead has a cryptographically assigned value, using complex algorithms and mathematics. The basic characteristics of a digital currency are:

• Decentralized

Traditional currency uses authorities and banks to control the flow of money. This is not the case with digital currency. Transactions are processed by an open network that not one single person owns. Most transactions take place on ‘nodes’, which are essentially computers spread around the world. The nodes verify transactions and make a note of these transactions on an open, decentralised record known as the blockchain.

• Irreversible and public

Digital currency transactions are public record, with a clear understanding of where the funds have travelled to and from, as well as the amount. The person who owns the currency is the only person allowed to move said currency; without a special key, the funds will remain in the digital wallet. Once the transaction is on the public blockchain, it will remain there indefinitely.  Transactions are hashed using a secure hashing algorithm, adding further security to the transaction.

• Anonymous

Sending and receiving digital currency is anonymous, as there is no centralised authority verifying the identity of users. Sending and receiving digital currency simply requires a digital wallet, and a wallet address.

• Limit supply

There is a limited supply and circulation of digital currency. This is usually defined by the creators of the cryptocurrency. This differs from traditional currencies, whereby banks can produce as much currency as they wish, in effect manipulating the financial characteristics of that currency. This is not the case with digital currency. As demand for the currency increases, the value of the currency increases.

How digital currencies are used

Digital currencies can be used very similarly to traditional currency. You can pay and receive payments for goods and services, to friends and family, and just about anything else.

First, the user must sign up to a digital currency exchange. This is essentially a place where users can purchase digital currency using traditional currency. For example, a user can buy some Bitcoin currency using Euro currency. A popular exchange is Coinbase.

Once a currency has been purchased, it resides in the users’ digital wallet. The user can send this currency to another digital wallet using a unique wallet address, which is automatically generated when a wallet is created. An example of a Bitcoin wallet address is as follows.

The user will send the Bitcoin to the wallet address - which is recorded on the blockchain - and is received in the recipient's wallet. The currency leaves the sender's wallet and is now in the possession of the receiver.

Bitcoin Pros

It is anonymous; decentralised; anyone can access digital currency; cannot be manipulated by large organisations.

Bitcoin Cons

Uses a lot of resources to compute the hashes required.

Some digital currencies are not accepted widely.

Value tends to fluctuate over short and long term.

Blockchain

Blockchain technology is used as a ledger to create a timestamped record of transactions.

Prior to blockchain technology, many people had tried to create digital currency but failed. The main issue behind these failures was the lack of trust. For example, if you created a new currency today called ‘Euro II’, what would stop you giving yourself a million Euro II? This lack of trust was rectified with the introduction of blockchain technology, which has led to a surge of successful digital currencies since 2009 onwards.

Blockchain basics

When data needs to be added to the blockchain, a new ‘piece’ - or block - is added to the chain, hence the term ‘blockchain’. Each connecting block is chronologically linked to one another, providing a reliable record of events. In terms of digital currency transactions, every single transaction can be viewed since the inception of Bitcoin in 2009, and remains unaltered. If anyone attempts to change the contents of a data block, a brand new transaction is added.

How it is used

Whilst blockchain technology is relatively new, it is based on centuries-old technology - the traditional ledger! In the past, someone may have used a single ledger to track data. Blockchain uses a worldwide, synchronised system of digital ledgers, making it incredibly reliable and accurate. This distribution of ledgers is what gives blockchain trust - it is completely tamper-proof. Once a transaction takes place, the blockchain is updated worldwide, with accurate information detailing the transaction in question.

How it tracks digital currency

Blockchain is a shared record of truth, which means people can place trust in its content. Every time a person undertakes a transaction, this is added to the blockchain. The block will contain various information, such as: 

●       Sender wallet address

●       Receiver wallet address

●       Amount sent

●       Network fee (the cost of sending the digital currency using the blockchain)

●       Timestamp 

●       Number of confirmations (the process of adding the transaction blocks to the blockchain, which is a mutual ‘agreement’ between blockchain nodes)

This information is added for each transaction, for every digital currency using blockchain technology. It is this action that provides users with trust and reassurance, alongside the immutable nature of the blockchain, allowing the widespread application of blockchain technology for digital currency tracking.

Cyber security

Here is a more detailed lesson about cyber security

Cyber security threats

Threats are the people or systems that might gain unauthorised access to our computer system. 

If that happens we say that our system has been compromised. 

When that happens it is because there is a weakness in our computer systems. If they are compromised the consequences might be:

• loss of data

• loss of confidence

• loss of access to the system

• identity theft

• loss of money

The cyber security threats we are going to study are:

• Brute-force attack

Attempting to gain access to a system using a list of the most common passwords or trying every possible combination of characters until the correct password is found. This attempt can be done on an email account, social media account, etc. We can try to prevent this by using strong passwords or using two-factor authentication (2FA) or 3FA.

• Data interception

Intercepting data whilst it is in-transit from source to destination.

• Distributed denial of service (DDoS) attack

Distributed Denial of Service attacks occur when multiple computer systems flood the target system with internet traffic, rendering it unable to respond to genuine requests, effectively taking it offline.

• Hacking

It is the act of gaining unauthorised access to a computer system.

• Malware

Malware is short for 'malicious software'. Virus, worms, Trojan horse, spyware, adware, ransomware are all malware.

• Pharming

When your computer is infected with malicious software, this will send you to a fake website when you typed in a url, for example, the url of your bank.

• Phishing

• Social engineering

Social engineering is the art of manipulating individuals into giving away private information such as login IDs and passwords.

Solutions that help to keep data safe from security threats

• Access levels

Users of a system will not have the same type of permissions when accessing a system. Access levels is about giving the appropriate permissions to each user of a system so they can only access the data that they need. For example, in a company, only the accountant will have the right to see the salaries of each employee. The sales department will be able to see all the information about the products they sell but not the full details of the employees.

• Anti-malware (anti-virus and anti-spyware)

This is software that continuously checks a computer system looking for malware. If it finds some, the anti-malware will quarantine or delete the malware.

• Authentication 

  • Username and password

Make sure you use strong passwords. To have a strong password the length should be at least eight characters and composed of a mix of letters, special characters and numbers.

• • Biometrics

Biometrics is the recording of your physical characteristics, like, fingerprints, facial recognition, retina scans. 

This data is used to identify individuals.

• • Two-step verification

When logging in into a system, apart from verifying your username and password the system sends you a verification code to your mobile phone or email. This helps to prevent brute force attacks and phishing.

• Automating software updates

The operating system of your computer system gives you the option to allow it to make automatic updates. This is because every day new malware appears on the scene. Your operating system is able to detect this and automatically update itself so it is well defended of the new threat.

• Checking the spelling and tone of communications

When opening emails check:

• the spelling and grammar

• the greeting, is it using your name or is it a general greeting? e.g. Dear Madam

• does it sound urgent?

• does it ask you to click on a link?

• Checking the URL attached to a link

Before clicking on a link you should check the URL. You can do this by hovering over the link with the mouse pointer.

• Firewalls

The network administrator sets a list of rules in the firewall. These rules decide who is able to access the computer system or network, therefore preventing unwanted visitors to the network.

• Privacy settings

Privacy settings are part of a social networking site or website that allow you to decide who is going to see information about you.

• Proxy-servers

A proxy server allows you to hide your IP address from the internet. 

This gives you many advantages, like, anonymity, since it will be the proxy that will communicate with the outside world on your behalf. Security, since attackers will not know your IP address they won't be able to attack you directly. 

• Secure socket layer (SSL) security protocol

SSL allows two parties to communicate using encryption. When you see a padlock next to the URL in a browser, it means that that website is using SSL security protocol.

HTTPS uses SSL to encrypt the resources that are requested to be transmitted.