LCA System Security & Firewall Management 3

Question 1

Which command lists all open firewalld zones and their active interfaces?

Accepted Answer

firewall-cmd --get-active-zones

Answer

firewall-cmd --get-active-zones shows each zone that has at least one interface or source assigned.

Question 2

What does setting 'PermitRootLogin no' in /etc/ssh/sshd_config accomplish?

Accepted Answer

Prevents direct root login via SSH while allowing su after login

Answer

This setting blocks SSH authentication as root but does not affect local console login or su/sudo elevation.

Question 3

Which auditd rule syntax watches for writes to /etc/passwd?

Accepted Answer

-w /etc/passwd -p wa -k passwd_changes

Answer

The -w flag specifies the watch path, -p wa means watch for writes and attribute changes, and -k sets the key label.

Question 4

Which kernel parameter, set via sysctl, disables ICMP echo (ping) responses?

Accepted Answer

net.ipv4.icmp_echo_ignore_all = 1

Answer

Setting icmp_echo_ignore_all to 1 instructs the kernel to silently discard all ICMP echo requests.

Question 5

In SELinux, what does the Boolean 'httpd_can_network_connect' control?

Accepted Answer

Whether the httpd process can initiate outbound network connections

Answer

This Boolean allows or denies the Apache httpd daemon from making outbound TCP connections, useful for reverse-proxy scenarios.

(LCA) Certified Linux Administrator Practice Test