Virtualization technology
虛擬化技術

You've explored a lot about operating systems. One more aspect to consider is that operating systems can run on virtual machines. In this reading, you’ll learn about virtual machines and the general concept of virtualization. You’ll explore how virtual machines work and the benefits of using them.
你已經深入了解了許多關於作業系統的知識。還有一個需要考慮的方面是作業系統可以在虛擬機器上運行。在這篇閱讀中，你將學習關於虛擬機器和虛擬化的一般概念。你將探索虛擬機器如何運作以及使用它們的好處。

What is a virtual machine?
什麼是虛擬機器？

A virtual machine (VM) is a virtual version of a physical computer. Virtual machines are one example of virtualization. Virtualization is the process of using software to create virtual representations of various physical machines. The term “virtual” refers to machines that don’t exist physically, but operate like they do because their software simulates physical hardware. Virtual systems don’t use dedicated physical hardware. Instead, they use software-defined versions of the physical hardware. This means that a single virtual machine has a virtual CPU, virtual storage, and other virtual hardware. Virtual systems are just code.
虛擬機器（VM）是實體電腦的虛擬版本。虛擬機器是虛擬化的一個例子。虛擬化是使用軟體來創建各種實體機器的虛擬表示的過程。「虛擬」這個詞指的是那些不存在於物理世界中的機器，但由於其軟體模擬了實體硬體，因此運作起來就像它們真實存在一樣。虛擬系統不使用專用的實體硬體，而是使用軟體定義的實體硬體版本。這意味著單一的虛擬機器擁有虛擬的 CPU、虛擬的儲存空間和其他虛擬硬體。虛擬系統僅僅是程式碼。

You can run multiple virtual machines using the physical hardware of a single computer. This involves dividing the resources of the host computer to be shared across all physical and virtual components. For example, Random Access Memory (RAM) is a hardware component used for short-term memory. If a computer has 16GB of RAM, it can host three virtual machines so that the physical computer and virtual machines each have 4GB of RAM. Also, each of these virtual machines would have their own operating system and function similarly to a typical computer.
您可以使用單一電腦的實體硬體來運行多個虛擬機器。這涉及將主機電腦的資源劃分，以便在所有實體和虛擬組件之間共享。例如，隨機存取記憶體（RAM）是一種用於短期記憶的硬體組件。如果一台電腦有 16GB 的 RAM，它可以承載三個虛擬機器，使得實體電腦和虛擬機器各自擁有 4GB 的 RAM。此外，每個虛擬機器都會有自己的作業系統，並且功能類似於典型的電腦。

Benefits of virtual machines
虛擬機的優勢

Security professionals commonly use virtualization and virtual machines. Virtualization can increase security for many tasks and can also increase efficiency.
安全專業人員通常使用虛擬化和虛擬機器。虛擬化可以提高許多任務的安全性，並且還可以提高效率。

Security  安全性

One benefit is that virtualization can provide an isolated environment, or a sandbox, on the physical host machine. When a computer has multiple virtual machines, these virtual machines are “guests” of the computer. Specifically, they are isolated from the host computer and other guest virtual machines. This provides a layer of security, because virtual machines can be kept separate from the other systems. For example, if an individual virtual machine becomes infected with malware, it can be dealt with more securely because it’s isolated from the other machines. A security professional could also intentionally place malware on a virtual machine to examine it in a more secure environment.
其中一個好處是虛擬化可以在實體主機上提供一個隔離的環境，或稱為沙盒。當一台電腦有多個虛擬機器時，這些虛擬機器是電腦的「客戶」。具體來說，它們與主機電腦和其他客戶虛擬機器是隔離的。這提供了一層安全性，因為虛擬機器可以與其他系統分開。例如，如果某個虛擬機器感染了惡意軟體，因為它與其他機器是隔離的，所以可以更安全地處理。安全專業人員也可以故意將惡意軟體放在虛擬機器上，以便在更安全的環境中檢查它。

Note: Although using virtual machines is useful when investigating potentially infected machines or running malware in a constrained environment, there are still some risks. For example, a malicious program can escape virtualization and access the host machine. This is why you should never completely trust virtualized systems.
注意：雖然在調查可能受感染的機器或在受限環境中運行惡意軟體時使用虛擬機器很有用，但仍然存在一些風險。例如，惡意程式可能會逃脫虛擬化並訪問主機機器。這就是為什麼你不應該完全信任虛擬化系統的原因。

Efficiency  效率

Using virtual machines can also be an efficient and convenient way to perform security tasks. You can open multiple virtual machines at once and switch easily between them. This allows you to streamline security tasks, such as testing and exploring various applications.
使用虛擬機器也是執行安全任務的一種高效且方便的方法。您可以同時開啟多個虛擬機器，並輕鬆在它們之間切換。這使您能夠簡化安全任務，例如測試和探索各種應用程式。

You can compare the efficiency of a virtual machine to a city bus. A single city bus has a lot of room and is an efficient way to transport many people simultaneously. If city buses didn’t exist, then everyone on the bus would have to drive their own cars. This uses more gas, cars, and other resources than riding the city bus. 
您可以將虛擬機的效率比作城市巴士。一輛城市巴士有很多空間，是同時運送許多人的一種高效方式。如果沒有城市巴士，那麼巴士上的每個人都必須自己開車。這樣會比乘坐城市巴士消耗更多的汽油、汽車和其他資源。

Similar to how many people can ride one bus, many virtual machines can be hosted on the same physical machine. That way, separate physical machines aren't needed to perform certain tasks.
就像許多人可以乘坐一輛巴士一樣，許多虛擬機可以被託管在同一台實體機器上。這樣就不需要單獨的實體機器來執行某些任務。

Managing virtual machines
管理虛擬機

Virtual machines can be managed with a software called a hypervisor. Hypervisors help users manage multiple virtual machines and connect the virtual and physical hardware. Hypervisors also help with allocating the shared resources of the physical host machine to one or more virtual machines.
虛擬機可以通過一種稱為虛擬機監控器的軟體來管理。虛擬機監控器幫助用戶管理多個虛擬機，並連接虛擬和實體硬體。虛擬機監控器還有助於將實體主機的共享資源分配給一個或多個虛擬機。

One hypervisor that is useful for you to be familiar with is the Kernel-based Virtual Machine (KVM). KVM is an open-source hypervisor that is supported by most major Linux distributions. It is built into the Linux kernel, which means it can be used to create virtual machines on any machine running a Linux operating system without the need for additional software.
一個值得你熟悉的虛擬機管理程式是 Kernel-based Virtual Machine（KVM）。KVM 是一個開源的虛擬機管理程式，受到大多數主要 Linux 發行版的支持。它內建於 Linux 核心中，這意味著可以在任何運行 Linux 作業系統的機器上創建虛擬機，而無需額外的軟體。

Other forms of virtualization
其他形式的虛擬化

In addition to virtual machines, there are other forms of virtualization. Some of these virtualization technologies do not use operating systems. For example, multiple virtual servers can be created from a single physical server. Virtual networks can also be created to more efficiently use the hardware of a physical network. 
除了虛擬機之外，還有其他形式的虛擬化。有些虛擬化技術不使用作業系統。例如，可以從單一實體伺服器創建多個虛擬伺服器。也可以創建虛擬網路，以更有效地利用實體網路的硬體。

Key takeaways  關鍵要點

Virtual machines are virtual versions of physical computers and are one example of virtualization. Virtualization is a key technology in the security industry, and it’s important for security analysts to understand the basics. There are many benefits to using virtual machines, such as isolation of malware and other security risks. However, it’s important to remember there’s still a risk of malicious software escaping their virtualized environments.
虛擬機器是實體電腦的虛擬版本，是虛擬化的一個例子。虛擬化是安全產業中的關鍵技術，安全分析師了解其基本原理非常重要。使用虛擬機器有許多好處，例如隔離惡意軟體和其他安全風險。然而，仍需記住惡意軟體有可能逃脫其虛擬化環境的風險。