Questions and Answers
What is the core of the Linux security system?
User account
What does UID stand for?
User ID
How many characters or fewer can a login name have in Linux?
Eight characters
What is the purpose of the /etc/passwd file?
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What is the UID assigned to the root user account?
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The /etc/shadow file provides more control over how the Linux system manages ___?
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Which of the following is NOT a field in the /etc/shadow file?
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The root user has access to the /etc/shadow file.
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What are the two subtypes of normal users in Linux?
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What is the role of a system user in Linux?
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Study Notes
Linux User Accounts
- Unique user accounts are essential for accessing a Linux system, with user permissions tied to these accounts.
- User IDs (UIDs) are unique numerical values assigned to each account, while login names (up to eight alphanumeric characters) are used for user authentication.
- User account management in Linux is facilitated through various special files and utilities.
/etc/passwd Fileno
- Stores the mapping of login names to corresponding UIDs, serving as a key component for user account management.
- Contains seven columns:
- Name
- Password (indicated by 'x' if set)
- UID
- GID (Group ID)
- Gecos (user information, can be empty)
- Home directory
- Shell (default path to the user's shell)
- The root user has a UID of 0, granting full administrative privileges.
/etc/shadow File
- Provides enhanced security for password management, accessible only by the root user.
- Each record includes:
- Login name
- Encrypted password
- Days since last password change
- Minimum days before a password can be changed
- Days until password must be changed
- Warning days before expiration
- Days after expiration before account is disabled
- Date of account disabling
- Reserved field for future use
- Enables fine control over password policies and account security.
Types of Linux Users
- Users are categorized as either administrators (superusers) with full control or non-administrators with limited access.
- Non-administrator accounts, composing the majority of user accounts, can be further classified into:
- Normal Users: Real individuals granted access to applications, files, and resources.
- System Users: Non-human accounts created for specific processes or programs, with restricted permissions.
Users and Groups Management
- Each Linux user is assigned a unique name, UID, a group, and a group identification (GID) upon creation.
- New accounts lead to the simultaneous creation of a new UID and a matching GID, establishing user-group relations essential for file permission control.
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Description
Explore the intricacies of Linux file permissions and user account management in this quiz. Understand how user IDs (UIDs) are assigned and how they impact access rights to various system objects. Test your knowledge on the core principles of Linux security.
