[ovs-dev] OVN: Document how to use firewalld service files

diff --git a/Documentation/automake.mk b/Documentation/automake.mk
index 6f38912f2..5f4d5e85d 100644
--- a/Documentation/automake.mk
+++ b/Documentation/automake.mk
@@ -46,6 +46,7 @@  DOC_SOURCE = \
 	Documentation/howto/index.rst \
 	Documentation/howto/docker.rst \
 	Documentation/howto/dpdk.rst \
+	Documentation/howto/firewalld.rst \
 	Documentation/howto/kvm.rst \
 	Documentation/howto/libvirt.rst \
 	Documentation/howto/selinux.rst \
diff --git a/Documentation/howto/firewalld.rst b/Documentation/howto/firewalld.rst
new file mode 100644
index 000000000..b78d8e3b4
--- /dev/null
+++ b/Documentation/howto/firewalld.rst
@@ -0,0 +1,110 @@ 
+..
+      Licensed under the Apache License, Version 2.0 (the "License"); you may
+      not use this file except in compliance with the License. You may obtain
+      a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+      WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+      License for the specific language governing permissions and limitations
+      under the License.
+
+      Convention for heading levels in Open vSwitch documentation:
+
+      =======  Heading 0 (reserved for the title in a document)
+      -------  Heading 1
+      ~~~~~~~  Heading 2
+      +++++++  Heading 3
+      '''''''  Heading 4
+
+      Avoid deeper levels because they do not render well.
+
+===================================
+Open Virtual Network With firewalld
+===================================
+
+firewalld is a service that allows for easy administration of firewalls. OVN
+ships with a set of service files that can be used with firewalld to allow
+for remote connections to the northbound and southbound databases.
+
+This guide will describe how you can use these files with your existing
+firewalld setup. Setup and administration of firewalld is outside the scope
+of this document.
+
+Installation
+------------
+
+If you have installed OVN from an RPM, then the service files for firewalld
+will automatically be installed in /usr/lib/firewalld/services. Installation
+from RPM includes installation from the yum or dnf package managers.
+
+If you have installed OVN from source, then from the top level source
+directory, issue the following commands to copy the firewalld service files:
+
+::
+
+    $ cp rhel/usr_lib_firewalld_services_ovn-central-firewall-service.xml \
+    /etc/firewalld/services/
+    $ cp rhel/usr_lib_firewalld_services_ovn-host-firewall-service.xml \
+    /etc/firewalld/services/
+
+
+Activation
+----------
+
+Assuming you are already running firewalld, you can issue the following
+commands to enable the OVN services.
+
+On the central server (the one running ovn-northd), issue the following
+
+::
+
+$ firewall-cmd --zone=public --add-service=ovn-central-firewall-service
+
+This will open TCP ports 6641 and 6642, allowing for remote connections to the
+northbound and southbound databases.
+
+On the OVN hosts (the ones running ovn-controller), issue the following
+
+::
+
+$ firewall-cmd --zone=public --add-service=ovn-host-firewall-service
+
+This will open UDP port 6081, allowing for geneve traffic to flow between the
+controllers.
+
+Variations
+----------
+
+When installing the XML service files, you have the choice of copying them to
+/etc/firewalld/services or /usr/lib/firewalld/services. The former is
+recommened since the latter can be overwritten if firewalld is upgraded.
+
+The above commands assumed your underlay network interfaces are in the
+"public" firewalld zone. If your underlay network interfaces are in a separate
+zone, then adjust the above commands accordingly.
+
+The \-\-permanent option may be passed to the above firewall-cmd invocations
+in order for the services to be permanently added to the firewalld
+configuration. This way it is not necessary to re-issue the commands eaach
+time the firewalld service restarts.
+
+The ovn-host-firewall-service only opens port 6081. This is because the
+default protocol for OVN tunnels is geneve. If you are using a different
+encapsulation protocol, you will need to modify the XML service file to open
+the appropriate port(s). For VXLAN, open port 4789. For STT, open port 7471.
+
+Recommendations
+---------------
+
+The firewalld service files included with the OVS repo are meant as a
+convenience for firewalld users. All that the service files do is to open
+the common ports used by OVN. No additional security is provided. To ensure a
+more secure environment, it is a good idea to do the following
+
+* Use tools such as iptables or nftables to restrict access to known hosts.
+* Use SSL for all remote connections to OVN databases.
+* Use role based access control for connections to the OVN southbound
+  database.
diff --git a/Documentation/howto/index.rst b/Documentation/howto/index.rst
index 5859a33dc..201d6936b 100644
--- a/Documentation/howto/index.rst
+++ b/Documentation/howto/index.rst
@@ -57,3 +57,4 @@  OVN
 
    docker
    openstack-containers
+   firewalld