Secure the network with firewalld

firewalld is a set of scripts and a daemon that manage netfilter on your RHEL system. It aims at creating a simple command-line interface to manage the firewall on your systems.

How to do it…

By default, firewalld is included in the "core" rpm group, but it may not be installed for some reason (that you left it out of your kickstart would be one!). Perform the following steps:

1. Install firewalld via the following command line:

   ~]# yum install -y firewalld
   

2. Now, enable firewalld through the following:

   ~]# systemctl enable firewalld
   

3. Finally, ensure that firewalld is started by executing the following command line:

   ~]# systemctl restart firewalld
   

Showing the currently allowed services and ports on your system

List all the allowed services using the following command:

~]# firewall-cmd –list-services

You can see the output as follows, where all the allowed services are listed:

Now, show the tcp/udp ports that are allowed by your firewall using the following command...