Mi firewall está actualmente inactivo.
systemctl status firewalld firewalld.service Loaded: masked (/dev/null) Active: inactive (dead)
Usé el siguiente comando para habilitar el firewall
# systemctl unmask firewalld
pero recibí este error:
# systemctl unmask firewalld
Failed to issue method call: Access denied
# sudo systemctl restart firewalld
Failed to issue method call: Unit firewalld.service failed to load: No such file or directory.
# sudo systemctl enable firewalld
Failed to issue method call: Access denied
lsmod | grep iptab
Muestra módulos cargados?