LFCS Question #445: Real Exam Question with Answer & Explanation

The correct answer is C: -rw-r--r--, -r--------. For shadowed passwords, /etc/passwd must be world-readable (-rw-r--r--) for system processes, while /etc/shadow must be readable only by root (-r--------) to protect sensitive password hashes.

Submitted by yasin.bd· Apr 18, 2026User and Group Management

Question

On a system using shadowed passwords, the correct permissions for /etc/passwd are ___ and the correct permissions for /etc/shadow are ___.

Options

A-rw-r-----, -r--------
B-rw-r--r--, -r--r--r--
C-rw-r--r--, -r--------
D-rw-r--rw-, -r-----r--
E-rw-------, -r--------

Explanation

For shadowed passwords, /etc/passwd must be world-readable (-rw-r--r--) for system processes, while /etc/shadow must be readable only by root (-r--------) to protect sensitive password hashes.

Common mistakes.

A. The permissions -rw-r----- for /etc/passwd restrict read access for 'others', which can cause issues for programs needing to map UIDs to usernames.
B. The permissions -r--r--r-- for /etc/shadow make the password hashes world-readable, posing a severe security risk.
D. The permissions -rw-r--rw- for /etc/passwd allow 'others' to write to the file, which is a significant security vulnerability, and -r-----r-- for /etc/shadow still allows 'others' to read it.
E. The permissions -rw------- for /etc/passwd restrict read access to only the owner (root), which can break system functionality requiring user lookup.

Concept tested. Linux password file permissions

Reference. https://man7.org/linux/man-pages/man5/shadow.5.html

Topics

#File Permissions#User Accounts#System Security#Shadow Passwords

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