RHCE EX300 Exam Preparation on RHEL 7 – getting your hands on firewall-cmd

RHEL 7 uses firewall-cmd for managing firewall rules, before you practice iptables should be disabled and stopped on your RHEL 7 servers.

1.using systemctl to stop the iptables :

#systemctl mask iptables ip6tables


2. how to verify what zones are enabled and what port/services are running ?

#sudo firewall-cmd --get-default-zone
public


3.List the ports and services

#sudo firewall-cmd --permanent --zone=public --list-all
public (default)
interfaces:
sources:
services: dhcpv6-client ssh
ports:
masquerade: no
forward-ports:
icmp-blocks:
rich rules:


 

4.Practice adding port 443 to your public zone using firewall-cmd


#firewall-cmd --permanent --zone=public --add-port 443/tcp


This book is an excellent resource for preparing for  RHCE exam, this book cover more practice questions I used for passing my RHCE exam, there is also a DVD included which you can take with you to learn topics like firewalld.