LPIC-2 System Security Practice Question
A company requires two-factor authentication for SSH logins. Which PAM module can be used to implement this if the system uses a time-based one-time password (TOTP)?
⚠ Common exam trap
Watch out — candidates often confuse generic authentication modules (like pam_radius.so or pam_ldap.so) with the specific TOTP module, or assume that any module supporting two-factor authentication (e.g., via RADIUS with tokens) is equivalent to the direct TOTP implementation provided by pam_google_authenticator.so.
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
✓
pam_google_authenticator.so
`pam_google_authenticator.so` is a PAM module specifically designed to implement time-based one-time password (TOTP) authentication as defined in RFC 6238. It integrates with SSH by requiring users to provide a six-digit code generated by the Google Authenticator app (or compatible TOTP client) in addition to their regular password, enabling two-factor authentication.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
pam_radius.so
Why it's wrong here
RADIUS is for centralized authentication, not TOTP.
- ✗
pam_ldap.so
Why it's wrong here
LDAP is for directory-based authentication.
- ✗
pam_krb5.so
Why it's wrong here
Kerberos is for ticket-based authentication, not TOTP.
- ✓
pam_google_authenticator.so
Why this is correct
This module provides TOTP-based two-factor authentication.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This LPIC-2 practice question is part of Courseiva's free LPI 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 LPIC-2 exam.