XK0-005 Reviews Questions

The correct answer is A. semanage port -a -t ssh_port_t -p tcp 2222

This command will allow the SSH server to bind to port 2222 by adding it to the SELinux policy. The semanage command is a utility for managing SELinux policies. The port subcommand is used to manage network port definitions. The -a option is used to add a new record, the -t option is used to specify the SELinux type, the -p option is used to specify the protocol, and the tcp 2222 argument is used to specify the port number. The ssh_port_t type is the default type for SSH ports in SELinux.

The other options are incorrect because:

B. chcon system_u:object_r:ssh_home_t /etc/ssh/*

This command will change the SELinux context of all files under /etc/ssh/ to system_u:object_r:ssh_home_t, which is not correct. The ssh_home_t type is used for user home directories that are accessed by SSH, not for SSH configuration files. The correct type for SSH configuration files is sshd_config_t.

C. iptables -A INPUT -p tcp --dport 2222 -j ACCEPT

This command will add a rule to the iptables firewall to accept incoming TCP connections on port 2222. However, this is not enough to fix the issue, as SELinux will still block the SSH server from binding to that port. Moreover, iptables may not be the default firewall service on some Linux distributions, such as Fedora or CentOS, which use firewalld instead.

D. firewall-cmd --zone=public --add-port=2222/tcp

This command will add a rule to the firewalld firewall to allow incoming TCP connections on port 2222 in the public zone. However, this is not enough to fix the issue, as SELinux will still block the SSH server from binding to that port. Moreover, firewalld may not be installed or enabled on some Linux distributions, such as Ubuntu or Debian, which use iptables instead.

The command docker run -d --restart always -p 5432:5432 -v /home/db:/var/lib/postgresql postgresql:12 ensures that the PostgreSQL container is started in detached mode (-d), it restarts automatically on system startup (--restart always), mounts the host directory /home/db to /var/lib/postgresql, and exposes port 5432. This is a typical setup for running a database in a Docker container.

The permanent rule --add-service=ntp --permanent is added, but such changes only take effect after a firewall reload.

D is correct: firewall-cmd --reload applies the permanent rule allowing traffic on UDP port 123, and systemctl restart ntpd ensures the NTP daemon is refreshed.

Incorrect Options:

A, B: These commands do not apply firewall rules.

C: --complete-reload is valid but overkill for applying one rule, and rarely used unless debugging.

The /etc/skel directory (note: the correct spelling is skel, not ske1) contains default files and folders that are copied into a new user’s home directory when the account is created.

A is intended to be /etc/skel and is correct if the typo is fixed.

Corrected Question Should Use: A. /etc/skel

Incorrect Options:

B: Used for network/system configuration.

C: Contains SSH server configuration and keys.

D: A script run at system boot — unrelated to user home configuration.