// Module included in the following assemblies:
//
// * microshift_networking/microshift-firewall.adoc

:_mod-docs-content-type: CONCEPT
[id="microshift-firewall-about_{context}"]
= About network traffic through the firewall

[role="_abstract"]
Firewalld is a networking service that runs in the background and responds to connection requests, creating a dynamic customizable host-based firewall. If you are using {op-system-ostree-first} with {microshift-short}, firewalld should be installed and you only need to configure it. 

Details are provided in procedures that follow. Overall, you must explicitly allow the following OVN-Kubernetes traffic when the `firewalld` service is running.

CNI pod to CNI pod::
CNI pod to Host-Network pod
Host-Network pod to Host-Network pod

CNI pod::
The Kubernetes pod that uses the CNI network

Host-Network pod::
The Kubernetes pod that uses host network
You can configure the `firewalld` service by using the following procedures. In most cases, firewalld is part of {op-system-ostree} installations. If you do not have firewalld, you can install it with the simple procedure in this section.

[IMPORTANT]
====
{microshift-short} pods must have access to the internal CoreDNS component and API servers.
====