Section two of the course is titled, protecting yourself from attack. In this part of the course, we're going to review the purpose of an operating system and we'll introduce virtual machines. We'll also look at some of the risks with using computers and the internet, and describe some of the common controls that can be put in place to secure devices and the people that use them. The objectives of this section are to understand operating systems, identify the benefits of using virtual machines, define authentication, authorisation, and accounting. Use permissions, rights, and inscription to protect data. Identify good practice for installing apps and protecting your devices against malware and data loss, describe how scripts and cookies can be used to collect data about your web-browsing and track you online, identify how easily personal data can be collected while online by social and other online platforms, describe the different types of social engineering and how it can be used to illicit personal information, and to understand the different types of phishing attacks and how to avoid them. In the first module, we're going to review the purpose of operating systems. We're also going to look how we can use virtual machines. At the end of this module, you'll be able to understand the purpose and core functions of an operating system, and understand the benefits of using virtual machines. So, what do we mean by an operating system? Well, all computers and computer-like devices have operating systems, including desktops, laptops, tablets, smartphones, and smartwatches. Computer devices are made up of hardware components, such as processors, memory and displays. The processor runs instructions by retrieving code from the computer's memory. The memory also contains data, which is used by the instructions. The computer will take input from devices, such as mice and keyboards, and then display information on the screen.

Now, us users, we wanna run apps on these computers, which make the hardware do things which might include sending information over a network. As you can see in the slide, the operating system sits between apps and the hardware. So, why don't we just let the apps control a hardware and get things done? Why do we need an operating system in the way? An operating system can be defined as software that managed computer hardware and provides common services for computer programmes.

Firstly, the operating system provides the interface between the hardware components, the software applications and the user, and handles many of the basic system functions. That means that software developers don't have to write the code for many of the operations their apps perform, like sending data over the network or storing it on a disc. Because this is all done for them by the operating system. Also, because these things are done by the operating system, they're done in a standard and efficient way, rather than depending on the skills of the coder. By providing an interface between software applications and hardware, the operating system can also control access to the hardware. And one important benefit of this is it allows the hardware to be shared by multiple software applications at the same time. We call this multitasking. On a computer device, there are lots of separate apps and processes that all need to share the computer's resources to get things done. Now, they can't all tell the processor what to do at the same time, and they need their own memory area, and they need to know what input's for them and what's not. They might need to display information on the screen alongside other apps. By keeping control, the operating system allows this to happen. Applications can't get access to the hardware directly and have to request a lot of the functionality form the operating system. This means the operating system can be configured with policies, to say what is and isn't allowed.

The operating system's also responsible for enforcing security. So, it controls what users and apps can do and what things they have access to. The operating system also displays information on the screen, using either a graphical user interface, called a GUI, or a command line interface, or CLI. A graphical interface like we see on our phones makes a device easy to use, as we can tap and click and see things as pictures.

A command line interface, it's more complicated to use but it can often provide access to more options. Some operating systems allow the computer to be shared by multiple users at the same time. Windows operating systems come in two major versions, that's desktop operating systems like Windows 10 and Windows 11, and server operating systems like Windows Server 2019 and Windows Server 2022. Desktop operating systems are designed and optimised to run desktop apps, like Word processors, web browsers, and games. Server operating systems might look similar to desktops but they're designed and optimised to run software that provides services on a network, like web servers, database servers, and mail servers. On a business network, usually computers that run server operating systems are also locked away in secure rooms to stop people from getting physical access to them. All access and administration is then done remotely over the network.

At home and school, you're most likely to use Microsoft Windows or Apple macOS on computers. Linux is also a popular operating system, which comes in lots of different flavours. And Kali is one of them. Kali is based on Debian Linux and it can be downloaded for free. Now, what's special about Kali is that it's pre-loaded with loads of tools that can be used for security testing. You can install it on a computer, a virtual machine, or you can just run it from a USB stick. The tools in Kali are very popular with security testers and also hackers, and we'll be using it in various labs throughout the course.

Something else we'll make sure of throughout the labs is virtual machines. So, what exactly is a virtual machine? We usually think about computer hardware as being used to run one operating system. At home, that's fine, but in a business world where lots of computers are needed, the cost of hardware can become very expensive along with electricity, space, cooling, and the support needed to run these computers. Modern computer hardware supports the use of a hypervisor. A hypervisor is a small piece of software that allows multiple operating systems to share access to the computer hardware at the same time. The operating systems that share the hardware through the hypervisor are called virtual machines. This means businesses can run many operating systems without the need to have separate hardware for each one, which reduces costs, space, cooling, and also makes better use of the hardware by having it shared.

Modern businesses and cloud companies make extensive use of virtual machines. There's a number of hypervisor products on the market, including Microsoft's Hyper-V and VMware ASX. In the labs, we'll be using Hyper-V. You'll get a chance to create and use virtual machines. There are many benefits to using virtual machines. As we've already seen, they can reduce the amount of computer hardware we need, which reduces costs and saves on electricity. But there are lots of benefits, some of which you can see in the slide. Virtual machine technology makes an operating system portable, which means it can be moved from one piece of hardware to another. With hypervisors, such as Hyper-V and ASX, this can be done while the operating system's running without losing access to anything. So, in a business, if we need to do any maintenance on a computer or if something fails, we can move the virtual machine to another computer without interrupting users. Businesses need to consider carefully how they isolate the software and data to help with security.

For example, it wouldn't be a good idea to run the company web server on the same operating system as a database, which contains secret information. If someone managed to hack into the web server from the internet, they'll probably be able to access the data in the database. Businesses, therefore, need to isolate different things using different operating systems. Now, in the past, this would need separate computers, whereas now it can be done using virtual machines. Virtual machines can also be a great way to test stuff without messing up your own computer. If you've got the professional edition of Windows, you can enable Hyper-V and build your own virtual machines, or you could install a little virtual box, which is free. On Macs we can also use virtual box or parallels desktop. If you use a virtual machine, you can install software on it, access the internet, and basically mess things up without needing to touch your real operating system. In addition, hypervisors can use snapshots, which take a point in time copy of the virtual machine. And then if you make any changes you don't like, you can just roll the machine back to the snapshot.

Virtual machines are used extensively in a business environment, but they can also be very useful for testing and research. Using virtual machines gives you a way to try things out safely without the risk of damaging your personal computer or affecting others. For the rest of the course, you're gonna be using virtual machines. But first we need to build them. In this lab, you'll create and import virtual machines into Microsoft Hyper-V. You're going to create a new Windows desktop virtual machine from scratch. And then the rest of the virtual machines have been created for you. So, you'll import these. On your lab computer, you'll use Hyper-V manager, which is the main tool for managing virtual machines in Hyper-V. You'll see that when you start Hyper-V manager, there's already a virtual machine listed, which is running. Just leave that one alone, it's there to get the business network going. You'll see that there's an action panel on the right-hand side, and the centre panel displays a list of virtual machines. In the centre panel, when you double-click a virtual machine, a new window will appear to show you the screen for that virtual machine.

In that window, there's a control to do a Control, Alt and Delete key sequence. And you can also access this on the action menu. The view menu has also got an option to put the virtual machine into full-screen mode. When you do this, it will take up the whole screen of your lab computer, and there'll be a blue bar at the top of the screen, which is a restore down option to take the machine back out of full-screen mode. Now, you might have to resize your lab computer's display using your browser zoom, to make sure everything fits. And it's really important to make sure you do things on the right machine. Once you're running a few virtual machines and get confused, and it's easy to try and do things on the wrong machine. So, make sure you follow the instructions carefully. As well as building a new Windows desktop in the lab, you're also going to import a Windows server machine. And you'll use this to host the business network services. If you have any problems with the import of virtual machines, please don't delete them, as this will also delete the files, and you won't be able to import them again. Throughout the labs, you're going to set up the network for our fictitious cyber security company called Serious CyberWorks. So, the server, it's going to be the first one on the Serious CyberWorks network. To get access to this section of the labs, you'll need to enter the access code 16639.

Module 1: Operating systems

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