OVN: Document how to use firewalld service files

Firewalld service files for OVN have been in the source for several
months. This adds instructions for how to use these service files with
firewalld.

Signed-off-by: Mark Michelson <mmichels@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

2 files changed, 108 insertions, 0 deletions

diff --git a/Documentation/howto/firewalld.rst b/Documentation/howto/firewalld.rst
new file mode 100644
index 000000000..b76a4d2b7
--- /dev/null
+++ b/Documentation/howto/firewalld.rst
@@ -0,0 +1,107 @@
+..
+      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 each
+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