UD05 - Users, Groups, and Permissions
One of the most important mechanisms for proper operating system management is the use of users, groups, and their associated permissions.Unit Objectives
User Management
Create, modify, and delete user accounts in Windows and Linux systems
Group Organization
Organize users into groups for efficient permission management
Permission Control
Grant and restrict access to files, folders, and system resources
Security Implementation
Implement security policies through proper access control
Why This Matters
The ability to grant permissions for reading, writing, modifying, executing, etc., to specific users and groups is one of the most important security features in an operating system.Proper user and permission management is fundamental to system security and organization.
Key Concepts
Users
Users are entities allowed to perform actions on processes and files. When you log in to an operating system, the system grants you resources and allows you to:- Launch programs
- Access files
- Modify data
- Execute applications
- Use hardware resources
Groups
Groups are collections of users that share common permissions. Instead of assigning permissions to individual users, you can:- Create a group
- Assign permissions to the group
- Add users to the group
- All group members inherit the permissions
Permissions
Permissions control what operations users can perform:Read
View file contents or list directory contents
Write
Modify files or create/delete files in directories
Execute
Run programs or access directories
Topics Covered
Windows Permissions
NTFS permissions, ACLs (Access Control Lists), inheritance, and security policies
Built-in Users and Groups
Windows
Built-in Users:- Administrator: Full system access
- Guest: Limited access for temporary users
- DefaultUser0: Template for new users
- Administrators
- Users
- Power Users
- Remote Desktop Users
- Backup Operators
Linux
Built-in Users:- root (UID 0): Superuser with full system access
- nobody: Unprivileged user for services
- System users for daemons and services
- sudo/wheel: Administrative privileges
- users: Regular users
- www-data: Web server processes
- adm: System monitoring
Access Control
Operating systems protect resources through access control mechanisms:Learning Outcomes
By the end of this unit, you will be able to:- Create and manage user accounts in Windows and Linux
- Organize users into groups effectively
- Configure file and folder permissions
- Implement security policies
- Troubleshoot permission issues
- Understand permission inheritance
- Use command-line tools for user management
Best Practices Preview
Principle of Least Privilege
Principle of Least Privilege
Grant users only the minimum permissions necessary to perform their tasks.
Use Groups, Not Individual Permissions
Use Groups, Not Individual Permissions
Assign permissions to groups rather than individual users for easier management.
Document Permission Structures
Document Permission Structures
Maintain documentation of who has access to what and why.
Regular Audits
Regular Audits
Periodically review user accounts and permissions to remove unnecessary access.
Separate Admin and User Accounts
Separate Admin and User Accounts
Administrators should use regular accounts for daily work and admin accounts only when needed.