Baclayo Reviewer PDF

platform - base of technology on which other technologies processes of built. Platform Layer - system software layer. manages hardware resources, such as memory, CPU, storage, and network. Example: -Operating system (linux, windows) -Databases server (Mysql) Application layer - actual software...

platform - base of technology on which other technologies processes of built. Platform Layer - system software layer. manages hardware resources, such as memory, CPU, storage, and network. Example: -Operating system (linux, windows) -Databases server (Mysql) Application layer - actual software application. Example: -Software Applications (Visual Studio Code) -Programming languages (Python, C++, Java, Javascript) Relationship between two layers application layer rely on the services provided by the platform layer. ABSTRACTION - dealing with generic forms rather than specific events, details or applications. BUNDING - Basic building blocks to build a component. INTEROPERABILITY - Software applications can run through other platforms. COMPONENTS OF A PLATFORM TECHNOLOGY INTERFACE - serves as a bridge between different components of a system \- can be categorized into various types, including user interfaces (UI) for human-computer interaction and application programming interfaces (APIs) for software-to-software communication. APPLICATION - software solutions and services that users interact with to perform specific tasks or functions. OPERATING SYSTEM - serving as an intermediary between hardware and software, process management, memory management, file system management, and device drivers. INFRASTRUCTURE - underlying hardware and networking components that support the platform and applications. INTERRELATIONSHIP/INTEROPERABILITY - communication between different layers of the platform, allowing applications to interact with the operating system and infrastructure First generation 1940s-1950s Vacuum tube based Second generation 1950s-1960s Transistor based Third generation 1960s-1970s Integrated circuit based Fourth generation 1970s-present Microprocessor based Fifth generation The present and the future HISTORY OF OPERATING SYSTEM \- An Operating System is a program that acts as an intermediary between a user of a computer and the computer hardware LESSON 2: COMPUTER SYSTEM STRUCTURE -Hardware -Operating System -Application programs -Users PRINCIPLES AND PROCESSES OF OPERATING SYSTEM Resource Management - hardware resources like CPU, memory, storage, and I/O devices. Abstraction - provide a level of abstraction for hardware resources, making it easier for users and applications to interact Concurrency - handles multiple tasks concurrently, allowing multiple processes and threads to execute simultaneously. Security and Protection - An OS must protect system resources and data from unauthorized access. Efficiency - must optimize resource use to maximize performance and throughput. User Interaction - provides interfaces for users to interact with the system COMPONENTS OF OPERATING SYSTEM Kernel - core component of an operating system that manages system resources Process Management - refers to the handling of processes by the OS, involves creating, scheduling, synchronizing, and terminating processes. Memory Management - managing system memory, including allocation, deallocation, and protection. Device Management - system refers to the functionality that controls and manages hardware devices attached to the computer system. User Interface - allows users to interact with the operating system and execute commands or applications. LESSON 3: CLIENT/SERVER BASICS - server is a program (or collection of cooperating programs) that provides services and/or manages resources on the behalf of other programs (its clients). EXAMPLE: AN ATM MACHINE \- clients are the ATM machines user interfaces some simple application processing \- server is at the bankmost application processing very large database of customer accounts ARCHITECTURAL REQUIREMENTS Reliable, robust communication between the clients and server Client/server cooperation Server controls services/data that the client accesses Server handles conflicting requests Application processing is usually distributed between a client and the server The 2-tier architecture - is simplified into two distinct layers: the client layer and the server layer. The 3-tier architecture - approach to building client-server applications. It separates the application into three distinct layers, each with its own responsibilities. The N-tier architecture - It involves breaking down an application into more than three layers or tiers, each with specific responsibilities Client \- A networked information requester, usually a PC or workstation, that can query database and/or other information from a server Server \- A computer, usually a high-powered workstation, a minicomputer, or a mainframe, that houses information for manipulation by networked clients Applications Programming Interface (API) \- A set of function and call programs that allow clients and servers to intercommunicate Middleware \- A set of drivers, APIs, or other software that improves connectivity between a client application and a server LESSON 4: Confidentiality - owner of data decides to make available only to certain people and no others, Integrity - unauthorized users should not be able to modify any data Availability - nobody can disturb the system to make it unusable, OPERATING SYSTEM SECURITY Passive attacks - try to steal information passively \- sniff the network traffic and tries to break the encryption to get to the data Active attacks - try to make a computer program misbehave \- take control of a user's Web browser to make it execute malicious code CONTROLLING ACCESS TO RESOURCES Protection Domains - domain is a set of (object, rights) pairs. Access Control Lists - list containing all the domains that may access the object, and how. Capabilities - list of objects associated with each process that may be accessed, AUTHENTICATION VS AUTHORIZATION two fundamental concepts in information security, often used together but serving different purposes. Authentication - process of verifying the identity of a user, system, or entity. It answers the question, \"Who are you?\" Purpose -- To confirm the identity of a user Authorization - process of determining what an authenticated user, system, or entity is allowed to do. It answers the question, \"What can you do?\" Purpose -- To determine access rights and permissions for authenticated entities COMMON ATTACKS Denial of Service (DoS) and Distributed Denial of Service (DDoS) - attacker overwhelms a system, network, or service with excessive requests, causing it to become unavailable to legitimate users. Ransomware - Malicious software encrypts files on a victim's system and demands a ransom for the decryption key. Insider Threats - Employees or other trusted individuals use their access to intentionally or unintentionally compromise security. Social Engineering - An attacker sends a fake email pretending to be from IT support, tricking users into revealing their passwords. DEFENSES Defense in depth - there should be multiple layers of security so that if one of them is breached, there are still others to overcome There are various layers of security that can be applied to an OS: Anti Virus Code Signing Model-based Intrusion Detection Sandboxing Firewalls Virtual Private Networks LESSON 5: Virtualization - the technology that allows multiple operating systems and applications to run simultaneously on a single physical computer. Benefits of Virtualization \* Cost Savings - allows for consolidation of hardware, reducing the need for multiple physical servers. \* Improved Resource Utilization - can be easily moved between physical servers, ensuring optimal resource allocation. \* Enhanced Scalability and Flexibility - enables businesses to quickly add or remove virtual machines as needed \*Simplified Server Management - easier to manage than physical servers Types of Virtualization Server Virtualization - Enables multiple operating systems and applications to run on a single physical server. Desktop Virtualization - Allows users to access their desktop environments from any device Network Virtualization - routers and switches, simplifying network management and improving performance. Hypervisors and Types of Virtual Machines Hypervisors are software that create and manage virtual machines. They act as a bridge between the physical hardware and the virtual machines, Type 1 Hypervisor - Runs directly on the hardware Type 2 Hypervisor - Runs as a software application within an operating system Virtualization Benefits - Hypervisors are the core component of virtualization, enabling the creation and management of virtual machines. Security Considerations in Virtualization Access Control - Restricting access to virtual machines and resources based on user roles and permissions. Network Security - Employing firewalls and intrusion detection systems to protect against malicious attacks. Data Encryption - Encrypting sensitive data stored on virtual machines to prevent unauthorized access. Antivirus Protection - Installing and maintaining antivirus software on both physical and virtual machines. Cloud Computing - Cloud computing is a model for delivering computing services, including servers, storage, databases, networking, software, analytics, and intelligence, over the internet. Infrastructure as a Service (IaaS) Provides access to fundamental computing resources, such as servers, storage, and networking. Platform as a Service (PaaS) Offers a platform for developing and deploying applications, including tools, runtime environments, and databases. Software as a Service (SaaS) Delivers software applications over the internet, eliminating the need for installation and maintenance. Characteristics of Clouds On-Demand Self - Service Users can access cloudresources whenever needed without requiring human interaction. Broad Network Access - Cloud services can be accessed from various devices and locations through the internet. Resource Pooling - Cloud providers pool physical resources and make them available to multiple users on demand. Rapid Elasticity - Cloud resources can be easily scaled up or down as needed, adapting to changing workloads. Cloud Computing Vs Virtualization Virtualization - A technology that allows multiple operating systems and applications to run on a single physical server. Cloud Computing \- A model for delivering computing services, including servers, storage, databases, networking, software, analytics, and intelligence, over the internet.