Creating and using service definitions for firewalld

Service definitions for firewalld are stored in the /usr/lib/firewalld/services directory. Let’s take a look at a simple service, such as the ssh service stored in the ssh.xml file, which has the following content:

<?xml version="1.0" encoding="utf-8"?>
<service>
  <short>SSH</short>
  <description>Secure Shell (SSH) is a protocol for logging into and executing commands on remote machines. It provides secure encrypted communications. If you plan on accessing your machine remotely via SSH over a firewalled interface, enable this option. You need the openssh-server package installed for this option to be useful.</description>
  <port protocol="tcp" port="22"/>
</service>

Here, we can see that we only need an XML file with three sections to describe a basic service:

• short: The short name for the...