Integration with PowerDNS module

Starting from version 2023.08.1, installation and configuration of the module is not supported. To integrate with the DNS server in the platform, use the Integration with DNSmanager 6 module.

If integration with PowerDNS was configured in the platform, the integration will continue to work until the Integration with DNSmanager 6 module is installed.

For some Internet services (e.g. sending email), in virtual machines (VMs) it is necessary to convert IP addresses into domain names. To perform this conversion, you need to configure VMmanager integration with the DNS server.

VMmanager supports integration with PowerDNS Authoritative Server. PowerDNS is a high-performance, free, open-source DNS server. Read more about PowerDNS in the official documentation.

After the integration, PTR records will be created on the DNS server, converting VM addresses into domain names.

The integration provides for the transfer of:

PTR records;
NS records, if additional name servers are specified in the module settings.

Transfer of other record types must be configured manually.

Matching of IP address and reverse domain name

To determine a domain name by IP address, the DNS server uses a PTR record of the reverse domain zone. To execute the request, the node address is converted to the reverse form. The translation method depends on the IP version.

IPv4

IPv4 address is written as four decimal numbers from 0 to 255, separated by dots. E.g., 192.168.0.1. To search for domain names by IPv4 addresses, the domain "in-addr.arpa." is used. The IP address is written in the domain name in reverse order. For example, the address 195.161.72.28 corresponds to the domain name "28.72.161.195.inaddr.arpa.".

IPv6

The IPv6 address is written as eight hexadecimal numbers from 0 to ffff, separated by colons. E.g., 3107:0c38:0a67:0000:0000:e446:3925:0091. To search for domain names by IPv6 addresses, the domain "ip6.arpa." is used. The IP address is written in the domain name in reverse order. For example, the address 3107:0c38:0a67:0000:0000:e446:3925:0091 corresponds to the domain name "1.9.0.0.5.2.9.3.6.4.4.e.0.0.0.0.0.0.0.7.6.a.0.8.3.c.0.7.0.1.3.ip6.arpa".

Configuring integration

Installing and configuring PowerDNS

The examples are commands for AlmaLinux 8. For other operating systems the commands may be different.
In the basic configuration PowerDNS uses BIND as backend. BIND does not support API write requests via HTTP, so it is not suitable for integration setup. The example describes changing the backend to Generic Mysql. Read more in the official PowerDNS documentation.

On a server for PowerDNS:

Add the epel-release repository:
```
dnf -y install epel-release
```
Install the software updates:
```
dnf -y update
```

Disable the SELinux service:

setenforce 0

sed -i 's/^SELINUX=.*/SELINUX=disabled/g' /etc/selinux/config

Install MySQL:

dnf -y install mysql-server mysql

systemctl enable mysqld.service

systemctl start mysqld.service

Perform the initial MySQL security setup:
```
mysql_secure_installation
```
Open the MySQL console:
```
mysql -u root -p
```

Create a database and a powernds account in the console:

CREATE DATABASE powerdns;

CREATE USER 'powerdns' IDENTIFIED BY '<powernds_mysql_pass>';

Comments to the command

GRANT ALL PRIVILEGES ON powerdns.* TO 'powerdns';

FLUSH PRIVILEGES;

Exit the console:
```
exit
```
Import the scheme for the data source:
1. Save the scheme from the PowerDNS documentation to /root/powerdns.sql.
  Each version of PowerDNS has its own scheme.
2. Import the saved file into the database:
```
mysql -u powerdns -p powerdns < /root/powerdns.sql
```

If the systemd-resolved service is enabled, stop and disable it:

systemctl disable systemd-resolved.service

systemctl stop systemd-resolved.service

systemctl mask systemd-resolved.service

Install PowerDNS:

dnf -y install pdns pdns-backend-mysql bind-utils

systemctl enable pdns.service

systemctl start pdns.service

Create the configuration file /etc/pdns/pdns.conf:

Configuration for primary DNS

api=yes
api-key=<pdns_api_key>  
webserver=yes
webserver-port=<pdns_port>
webserver-address=0.0.0.0
webserver-allow-from=0.0.0.0/0

launch=gmysql
gmysql-host=127.0.0.1
gmysql-user=powerdns
gmysql-password=<powernds_mysql_pass>
gmysql-dbname=powerdns

primary=yes
allow-axfr-ips=<transfer_zone_allow>

Configuration for secondary DNS

api=yes
api-key=<pdns_api_key>  
webserver=yes
webserver-port=<pdns_port>
webserver-address=0.0.0.0
webserver-allow-from=0.0.0.0/0

launch=gmysql
gmysql-host=127.0.0.1
gmysql-user=powerdns
gmysql-password=<powernds_mysql_pass>
gmysql-dbname=powerdns  

secondary=yes

Comments

Open the DNS and PowerDNS web server ports in the firewall:
```
firewall-cmd --permanent --zone=public --add-port=<pdns_port>/tcp
```
Comments to the command
<pdns_port> — port of access to the built-in PowerDNS web server
```
firewall-cmd --permanent --zone=public --add-service=dns
```
```
firewall-cmd --reload
```
If PowerDNS is used as a secondary DNS:
1. Add domain zones:
```
pdnsutil create-secondary-zone <zone> <primary_dns>
```
  Comments to the command
  
  <zone> — domain zone
  <primary_dns> — IP address of the primary DNS server
2. Open the MySQL console:
```
mysql -u root -p
```
3. Add a record to the database with the settings of the main server:
```
INSERT INTO supermasters VALUES ('<primary_IP>', '<primary_domain>', 'powerdns') ;
```
  Comments to the command
  
  <primary_IP> — IP address of the primary DNS server
  <primary_domain> — domain name of the primary DNS server
4. Exit the console:
```
exit
```
5. In the /etc/pdns/pdns.conf file, set autosecondary to yes:
```
autosecondary=yes
```
Restart PowerDNS:
```
systemctl restart pdns.service
```

Configuration VMmanager

Starting from version 2023.08.1, configuration is only possible via the platform API.

Send data to VMmanager to connect to PowerDNS API:
```
curl -d '{"type":"powerdns", "params":{"address":"<pdns_ip>:<pdns_port>", "password":"<pdns_api_key>"}, "nameservers":["<ns1>","<ns2>"]}' -H "x-xsrf-token: <token>" -H "Host: instance-1" https://<vmmgr_ip>/dnsproxy/v3/settings/dns
```
Where

<pdns_ip>:<pdns_port> — IP address and PowerDNS port
<pdns_api_key> — PowerDNS API access key
<token> — authorization token. Read more in API guide
<vmmgr_ip> — IP address or domain name of the server with VMmanager
<ns1>,<ns2> — IP addresses or domain names of NS

If you get the message "Instance is starting now" in response, repeat the command.
Enable the dnsproxy service on the server with VMmanager. This service performs integration with external DNS servers.
```
curl -X POST -H "x-xsrf-token: <token>" https://<vmmgr_ip>/ip/v3/plugin/dnsproxy/enable
```
Where

<token> — authorization token
<vmmgr_ip> — IP address or domain name of the server with VMmanager
Start data synchronization with dnsproxy. After that, dnsproxy service will transfer PTR records to PowerDNS:
```
curl -X POST -H "x-xsrf-token: <token>" https://<vmmgr_ip>/ip/v3/ip/dnsproxy/sync
```
Where

<token> — authorization token
<vmmgr_ip> — IP address or domain name of the server with VMmanager

Checking settings

Check that ip6.arpa. and inaddr.arpa. DNS zones are added to PowerDNS:

curl -v -H 'X-API-Key: <pdns_api_key>' http://<pdns_ip>:<pdns_port>/api/v1/servers/localhost/zones

Where

If the zones are added successfully, the response should contain information about their settings:

An example of response

Check the creation of DNS records in ip6.arpa. and inaddr.arpa.:

curl -v -H 'X-API-Key: <pdns_api_key>' http://<pdns_ip>:<pdns_port>/api/v1/servers/localhost/zones/in-addr.arpa.

curl -v -H 'X-API-Key: <pdns_api_key>' http://<pdns_ip>:<pdns_port>/api/v1/servers/localhost/zones/ip6.arpa.

Where

The response must contain PTR records for the VMs’ IP addresses.

An example of response for the inaddr.arpa zone

Check operation of PowerDNS:
```
dig -x <IP> @<pdns_ip> +short
```
Where

<IP> — IP address of the VM
<pdns_ip> — IP address of PowerDNS

The response must contain information about the PTR record for the requested IP address.

Diagnostics

VMmanager integration with PowerDNS is performed by the dnsproxy service. You can check the operation of dnsproxy service via the /var/log/dns_proxy_service_1_writer.log file in the vm_dns_proxy_1 docker container on the server with VMmanager.

To check the DNS zone settings in VMmanager, run the command on the server with VMmanager:

docker exec -it mysql bash -c "mysql isp -p\$MYSQL_ROOT_PASSWORD -e 'select * from dns_proxy_zone;' "

An example of response

*************************** 1. row ***************************
         id: 1
     status: ok
status_info: null
       name: in-addr.arpa
*************************** 2. row ***************************
         id: 2
     status: ok
status_info: null
       name: ip6.arpa
2 rows in set (0.00 sec)

Where

To check the DNS records settings in VMmanager, run the command on the server with VMmanager:

docker exec -it mysql bash -c "mysql isp -p\$MYSQL_ROOT_PASSWORD -e 'select * from dns_proxy_record;' "

An example of the command output:

An example of response

*************************** 1. row ***************************
         id: 1
     status: ok
status_info: null
       zone: 1
       name: 172.31.255.254
    content: gateway.reserved.example.com
       type: ptr
*************************** 2. row ***************************
         id: 2
     status: ok
status_info: null
       zone: 1
       name: 172.31.240.0
    content: subnet.reserved.example.com
       type: ptr

Where

If you have problems configuring the integration:

Disable the dnsproxy service:
```
curl -X POST -H "x-xsrf-token: <token>" https://<vmmgr_ip>/ip/v3/plugin/dnsproxy/disable
```
Where

<token> — authorization token
<vmmgr_ip> — IP address or domain name of the server with VMmanager

Delete the contents of dns_proxy_record and dns_proxy_zone tables:

docker exec -it mysql bash -c "mysql isp -p\$MYSQL_ROOT_PASSWORD -e 'delete from dns_proxy_record; delete from dns_proxy_zone;' "

Reconfigure the integration.