Linux Security 5

Question 1

Which command forces all users to change their passwords on their next login?

Accepted Answer

chage -d 0 username

Answer

chage -d 0 sets the last password change date to epoch, forcing an immediate password change at next login.

Question 2

What is the risk of having NOPASSWD in a sudoers entry?

Accepted Answer

The user can run sudo commands without entering a password, bypassing authentication

Answer

NOPASSWD allows a user to invoke sudo without a password, which eliminates a key authentication checkpoint.

Question 3

Which nmap flag performs a SYN (stealth) scan without completing the TCP handshake?

Accepted Answer

-sS

Answer

nmap -sS sends SYN packets and never completes the handshake, making the scan less likely to appear in connection logs.

Question 4

What does 'gpg --verify file.sig file' accomplish?

Accepted Answer

Checks that the file's signature matches the signer's public key

Answer

gpg --verify validates the detached signature file against the data file using the signer's public key in your keyring.

Question 5

Which file defines password complexity and aging policies for PAM-based authentication on RHEL/CentOS?

Accepted Answer

/etc/security/pwquality.conf

Answer

pwquality.conf controls minimum length, character class requirements, and other complexity rules enforced by pam_pwquality.

Linux Practice Test