Practice Test Geeks(LCA) Certified Linux Administrator Practice Test
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System Security & Firewall Management Flashcards

7 cards from real LCA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 System Security & Firewall Management flashcards as text

  1. Which fail2ban component reads log files and triggers bans based on defined filters?

    Answer: fail2ban-server

    fail2ban-server is the daemon that monitors logs and communicates with the firewall to block offending IPs.

  2. What does 'restorecon -Rv /var/www/html' do?

    Answer: Restores SELinux file contexts based on policy for the directory tree

    restorecon applies the correct SELinux contexts as defined in the policy database, -R for recursive, -v for verbose.

  3. Which SSH configuration directive restricts login to specific users?

    Answer: AllowUsers

    The AllowUsers directive in sshd_config accepts a space-separated list of usernames permitted to authenticate via SSH.

  4. A server is experiencing a SYN flood attack. Which sysctl parameter helps mitigate this?

    Answer: net.ipv4.tcp_syncookies = 1

    TCP SYN cookies allow the server to handle SYN floods without maintaining half-open connection state in the backlog queue.

  5. Which command in nftables lists all current rules across all tables?

    Answer: nft list ruleset

    nft list ruleset outputs the complete nftables configuration including all tables, chains, and rules.

  6. What file stores the public keys authorized for key-based SSH login for a specific user?

    Answer: ~/.ssh/authorized_keys

    The ~/.ssh/authorized_keys file holds public keys whose corresponding private keys are accepted for authentication.

  7. Which command shows which SELinux Boolean values are currently enabled?

    Answer: getsebool -a

    getsebool -a lists all SELinux Booleans and their current (on/off) state.