How to add PTR records

How to add PTR records for an existing floating IP

Overview

This Document will show you the essential steps to add a PTR record for an existing floating IP.

For a complete overview see the networking reference guide and the DNS reference guide.

Prerequisites

• You know the basics of using the OpenStack CLI-Tools.
• You know the basics of the Designate DNS service as shown in the DNSaaS tutorial.

You may need to install the designate client (plugin).

(sudo) pip install python-openstackclient python-designateclient

Create your zone

We only allow PTR records for zones that you own. You can use a zone that you already created before this how-to.

If you want to create a subzone for the purpose of delegating it to a different project, you may want to work through this howto first.

If you want to practice with a test domain, you can create an empty zone like this:

$ openstack zone create --email email@domain.example ptrhowto.example.
+----------------+--------------------------------------+
| Field          | Value                                |
+----------------+--------------------------------------+
| action         | CREATE                               |
| attributes     |                                      |
| created_at     | 2019-06-28T15:27:00.000000           |
| description    | None                                 |
| email          | email@domain.example                 |
| id             | 01234567-89ab-cdef-0123-456789abcdef |
| masters        |                                      |
| name           | ptrhowto.example.                    |
| pool_id        | 14234f0f-1234-4444-6789-758006f43802 |
| project_id     | 0123456789abcdef0123456789abcdef     |
| serial         | 1561735620                           |
| status         | PENDING                              |
| transferred_at | None                                 |
| ttl            | 21600                                |
| type           | PRIMARY                              |
| updated_at     | None                                 |
| version        | 1                                    |
+----------------+--------------------------------------+

Create a network and a server

You need at least one network and one server. For testing purposes, you can create a network and a server by following the tutorials "first steps" or "single LAMP server".

Set DNS domain property of the network

For automated forward A-record and reverse PTR-record management, the DNS domain needs to be associated with the network.

Find out the network ID with this command:

openstack network list

Then associate the DNS zone with the network:

openstack network set --dns-domain ptrhowto.example. <Network UUID>

Set the DNS domain and DNS name of the port

Because we did not use the DNS integration when the server was created, we must update the DNS domain and DNS name for the preexisting network port of our server. For newly created servers this will happen automatically, once we associated the DNS domain with the network.

First let's find the ID of the server we want to work with and the floating IP:

$ openstack server list
+--------------------------------------+------------+--------+--------------------------------------------------+----------------------------------+----------+
| ID                                   | Name       | Status | Networks                                         | Image                            | Flavor   |
+--------------------------------------+------------+--------+--------------------------------------------------+----------------------------------+----------+
| e4dc0ac3-7f71-4279-ba95-d686da868dae | appserver2 | ACTIVE | demo_net=192.168.2.30, 185.56.129.73  | Ubuntu Bionic 18.04 (2020-04-30) | m1c.tiny |
+--------------------------------------+------------+--------+--------------------------------------------------+----------------------------------+----------+

And now we need to find the network port ID:

$ openstack port list --server e4dc0ac3-7f71-4279-ba95-d686da868dae
+--------------------------------------+------+-------------------+-----------------------------------------------------------------------------+--------+
| ID                                   | Name | MAC Address       | Fixed IP Addresses                                                          | Status |
+--------------------------------------+------+-------------------+-----------------------------------------------------------------------------+--------+
| 1e1c5f3f-4b69-41d0-8e67-15911a471a42 |      | fa:16:3e:8e:29:33 | ip_address='192.168.2.30', subnet_id='81bcf2d9-f72e-4a2c-aedd-1f68e4c7f86d' | ACTIVE |
+--------------------------------------+------+-------------------+-----------------------------------------------------------------------------+--------+

Now we can update the DNS domain and DNS name for our port:

openstack port set 1e1c5f3f-4b69-41d0-8e67-15911a471a42 --dns-domain ptrhowto.example. --dns-name appserver2

Re-assign the floating IP

Finally, to create the forward A-type records and reverse PTR-type records for our Floating IP, we need to re-assign it to the server:

In our example, the server ID is e4dc0ac3-7f71-4279-ba95-d686da868dae and the floating IP is 185.56.129.73.

openstack server remove floating ip <server UUID> <server floating IP>

and then immediately run:

openstack server add floating ip <server UUID> <server floating IP>

Conclusion

We now created the forward A-type record appserver2.ptrhowto.example. in our example zone. You can verify that by running:

openstack recordset list ptrhowto.example.

Also, a matching reverse PTR-type record is configured for the floating IP:

$ dig +short -x 185.56.129.73
appserver2.ptrhowto.example.