hardMultiple ChoiceObjective-mapped
SSCP Practice Question: A Linux server administrator configures SSH…
A Linux server administrator configures SSH key-based authentication for user 'admin'. The authentication fails with the error 'Authentication refused: bad permissions' in the logs. What is the most likely cause?
⚠ Common exam trap
ISC2 often tests the distinction between file permission errors and other authentication failures, trapping candidates who confuse 'bad permissions' with missing keys or incorrect passphrases.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The private key file has permissions set to 644 (world-readable)
SSH key-based authentication requires the private key file to have restrictive permissions (typically 600 or 640) to prevent unauthorized access. When the private key is world-readable (e.g., 644), the SSH daemon refuses to use it for security reasons, logging 'Authentication refused: bad permissions'. This is a direct check performed by OpenSSH to protect against key disclosure.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The SSH service is not running
Why it's wrong here
If SSH service were down, the connection would be refused entirely, not specific key permission errors.
- ✓
The private key file has permissions set to 644 (world-readable)
Why this is correct
SSH daemon checks private key permissions; if too permissive, it refuses authentication for security.
- ✗
The public key is not in the ~/.ssh/authorized_keys file
Why it's wrong here
A missing public key would result in 'Permission denied (publickey)' but not a 'bad permissions' error.
- ✗
The passphrase on the private key is incorrect
Why it's wrong here
An incorrect passphrase would prompt for a passphrase multiple times or fail with 'Permission denied' but not 'bad permissions'.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SSCP practice question is part of Courseiva's free ISC2 certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SSCP exam.