Linux Security 3

Question 1

Which command shows all open network ports and the processes listening on them?

Accepted Answer

ss -tlnp

Answer

ss -tlnp shows TCP listening ports (-t -l), numeric addresses (-n), and the owning process (-p).

Question 2

What is the correct permission octal value for a file readable and writable by owner only?

Accepted Answer

600

Answer

600 grants read (4) and write (2) to the owner only; group and others have no permissions.

Question 3

Which AppArmor command places a profile into enforce mode?

Accepted Answer

aa-enforce /etc/apparmor.d/profile

Answer

aa-enforce activates an AppArmor profile in enforce mode, blocking policy violations.

Question 4

What does the 'umask 027' command do?

Accepted Answer

New files get permissions 640 and new directories get 750

Answer

umask 027 masks out write for group and all permissions for others, resulting in 640 for files and 750 for directories.

Question 5

Which log file records failed and successful sudo usage on most Linux distributions?

Accepted Answer

/var/log/auth.log or /var/log/secure

Answer

Authentication events including sudo use are written to /var/log/auth.log (Debian-based) or /var/log/secure (RHEL-based).

Linux Practice Test