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Subject - Operating Systems CS 4001(Same as CB/IT 4001)
Branch - Computer Science Engineering
Semester - 4th Semester
UNIT 5: Operating System Security
This unit focuses on the various aspects of security within an operating system. It explores key concepts such as authentication, access control, access rights, and the use of system logs. Understanding these concepts helps in protecting the OS from unauthorized access, misuse, and ensuring the integrity of the system.
5.1 OS Security 🛡️
Operating System Security refers to the measures and mechanisms implemented by the operating system to protect itself from unauthorized access, threats, and vulnerabilities. OS security ensures the confidentiality, integrity, and availability of data and resources on a system.
Key Components of OS Security:
- Confidentiality: Ensures that sensitive data is accessible only by authorized users or systems.
- Integrity: Ensures that data is not tampered with or altered by unauthorized users.
- Availability: Ensures that the system and its resources are available to authorized users when needed.
Types of OS Security Mechanisms:
- Encryption: Protecting data by converting it into a code that only authorized users can decode.
- User Authentication: Verifying the identity of users before granting them access to the system.
- Access Control: Defining and enforcing permissions on users and their access to system resources.
5.2 Authentication 🗝️
Authentication is the process of verifying the identity of a user, device, or system before granting access to resources. The goal is to ensure that only authorized entities can interact with the system.
Types of Authentication Methods:
- Password-based Authentication: The most common method, where the user enters a password that is compared to a stored hash in the system.
- Biometric Authentication: Uses unique physical traits (e.g., fingerprint, retina scan, facial recognition) to authenticate users.
- Two-Factor Authentication (2FA): Combines two different methods (e.g., a password and a one-time code sent to a phone) to enhance security.
- Multi-Factor Authentication (MFA): Uses multiple factors for authentication, such as something you know (password), something you have (token), and something you are (biometric).
Why is Authentication Important?
- It helps protect user data and system resources.
- It ensures that only legitimate users can access sensitive information or perform critical operations.
5.3 Access Control 🔐
Access Control is the process of defining and enforcing who can access resources in the system and what actions they can perform on those resources. It ensures that only authorized users or systems can access certain data or functionalities.
Types of Access Control Models:
- Discretionary Access Control (DAC): The owner of a resource decides who can access it. For example, file permissions in Unix-like systems (read, write, execute).
- Mandatory Access Control (MAC): Access decisions are made based on pre-defined security policies, not the resource owner. For instance, SELinux (Security-Enhanced Linux) uses MAC.
- Role-Based Access Control (RBAC): Access is granted based on roles assigned to users. For example, an administrator has higher privileges than a regular user.
- Attribute-Based Access Control (ABAC): Access decisions are based on attributes (e.g., user’s department, time of access).
Access Control Lists (ACLs): ACLs specify which users or groups can access a particular resource and what actions they can perform on it (e.g., read, write, execute).
5.4 Access Rights 🔑
Access Rights (or Permissions) are the privileges granted to users or systems for accessing and manipulating resources (files, programs, databases) on the OS. These rights determine what actions users can perform on specific objects.
Types of Access Rights:
- Read (R): Allows the user to view the contents of a file or directory.
- Write (W): Allows the user to modify the contents of a file or directory.
- Execute (X): Allows the user to execute a program or script.
- Delete (D): Allows the user to delete a file or directory.
Example of Access Rights in Unix/Linux:
- Owner: Full rights (read, write, execute).
- Group: Limited rights (read, execute).
- Others: Minimal rights (read-only or no access).
The goal is to grant the minimum necessary permissions to prevent unauthorized access while allowing legitimate users to perform required tasks.
5.5 System Logs 📝
System Logs are records generated by the operating system that capture detailed information about events occurring within the system. These logs are essential for monitoring, troubleshooting, and maintaining security.
Types of System Logs:
- Authentication Logs: These logs capture user login attempts, including successful and failed logins.
- Access Logs: These logs track the access to files, directories, or other resources on the system.
- Audit Logs: These logs record actions performed by users, including file access, modifications, and deletions.
- Error Logs: These logs capture system errors, such as application crashes or hardware failures.
- Security Logs: These logs monitor security-related activities, including unauthorized access attempts or potential threats.
Importance of System Logs:
- Security Monitoring: Logs help detect unauthorized access or malicious activities.
- Troubleshooting: Logs are essential for diagnosing and resolving system issues.
- Compliance: Logs may be required to meet legal or regulatory requirements (e.g., in finance or healthcare).
Conclusion 🎯
Operating system security is essential for protecting sensitive data and resources from unauthorized access. It involves mechanisms like authentication, access control, access rights, and system logging to ensure the system is secure and functional.
- Authentication verifies the identity of users or systems.
- Access Control defines what resources users can access and what actions they can perform.
- Access Rights grant specific privileges to users for resources.
- System Logs record activities and provide insights into the security and functionality of the system.
By understanding and implementing these concepts, you can help safeguard the operating system and its resources against various threats.
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