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

1. The examples are commands for AlmaLinux 8. For other operating systems the commands may be different.
2. 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:

1. Add the epel-release repository:

   dnf -y install epel-release

   BASH

2. Install the software updates:

   dnf -y update

   BASH

3. Disable the SELinux service: 

   setenforce 0

   CODE

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

   CODE

4. Install MySQL:

   dnf -y install mysql-server mysql

   BASH

   systemctl enable mysqld.service

   BASH

   systemctl start mysqld.service

   BASH

5. Perform the initial MySQL security setup:

   mysql_secure_installation

   BASH

6. Open the MySQL console:

   mysql -u root -p

   BASH

7. Create a database and a powernds account in the console:

   CREATE DATABASE powerdns;

   SQL

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

   SQL
    Comments to the command

   <powernds_mysql_pass> — password to the powerdns account in MySQL

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

   SQL

   FLUSH PRIVILEGES;

   SQL

8. Exit the console:

   exit

   SQL
9. 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

      BASH

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

    systemctl disable systemd-resolved.service

    BASH

    systemctl stop systemd-resolved.service

    BASH

    systemctl mask systemd-resolved.service

    BASH

11.  Install PowerDNS:

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

    BASH

    systemctl enable pdns.service

    BASH

    systemctl start pdns.service

    BASH

12. 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>

    CODE

    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

    CODE
     Comments

    <pdns_api_key> — PowerDNS API access key. Minimum length — 6 characters

    <pdns_port> — port of access to the built-in PowerDNS web server

    <powernds_mysql_pass> — password to the powerdns account in MySQL

    <transfer_zone_allow> — IP addresses of DNS servers that are allowed to request a domain zone transfer

13. Open the DNS and PowerDNS web server ports in the firewall:

    firewall-cmd --permanent --zone=public --add-port=<pdns_port>/tcp

    BASH
     Comments to the command

    <pdns_port> — port of access to the built-in PowerDNS web server

    firewall-cmd --permanent --zone=public --add-service=dns

    BASH

    firewall-cmd --reload

    BASH

14.  If PowerDNS is used as a secondary DNS:

    1. Add domain zones:

       pdnsutil create-secondary-zone <zone> <primary_dns>

       BASH
        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

       SQL

    3. Add a record to the database with the settings of the main server: 

       INSERT INTO supermasters VALUES ('<primary_IP>', '<primary_domain>', 'powerdns') ;

       CODE
        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

       SQL

    5. In the /etc/pdns/pdns.conf file, set autosecondary to yes: 

       autosecondary=yes

       CODE

15.  Restart PowerDNS:

    systemctl restart pdns.service

    BASH

Configuration VMmanager

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

1. 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

   CODE
    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.

2. 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

   CODE
    Where

   <token> — authorization token

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

3. 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

   CODE
    Where

   <token> — authorization token

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

Checking settings

1. 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

   CODE
    Where

   <pdns_api_key> — PowerDNS API access key

   <pdns_ip>:<pdns_port> — IP address and PowerDNS port

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

    An example of response

   [{
   "account": "",
   "dnssec": false,
   "id": "ip6.arpa.",
   "kind": "Master",
   "last_check": 0,
   "masters": [],
   "name": "ip6.arpa.",
   "notified_serial": 0,
   "serial": 2020032801,
   "url": "/api/v1/servers/localhost/zones/ip6.arpa."
   },
   {
   "account": "",
   "dnssec": false,
   "id": "in-addr.arpa.",
   "kind": "Master",
   "last_check": 0,
   "masters": [],
   "name": "in-addr.arpa.",
   "notified_serial": 0,
   "serial": 2020032812,
   "url": "/api/v1/servers/localhost/zones/in-addr.arpa."
   }]

   CODE

2. 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.

   CODE

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

   CODE
    Where

   <pdns_api_key> — PowerDNS API access key

   <pdns_ip>:<pdns_port> — IP address and PowerDNS port

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

   
   

    An example of response for the inaddr.arpa zone

   {
   "account": "",
   "api_rectify": false,
   "dnssec": false,
   "id": "in-addr.arpa.",
   "kind": "Master",
   "last_check": 0,
   "masters": [],
   "name": "in-addr.arpa.",
   "notified_serial": 0,
   "nsec3narrow": false,
   "nsec3param": "",
   "rrsets": [
   {
   "comments": [],
   "name": "14.250.31.172.in-addr.arpa.",
   "records": [
   {
   "content": "sunshine-ametrine.example.com.",
   "disabled": false
   }
   ],
   "ttl": 3600,
   "type": "PTR"
   },
   {
   "comments": [],
   "name": "0.250.31.172.in-addr.arpa.",
   "records": [
   {
   "content": "subnet.reserved.example.com.",
   "disabled": false
   }
   ],
   "ttl": 3600,
   "type": "PTR"
   },
   ...
   ],
   "serial": 2020032717,
   "soa_edit": "",
   "soa_edit_api": "DEFAULT",
   "url": "/api/v1/servers/localhost/zones/in-addr.arpa."
   }

   CODE

3. Check operation of PowerDNS:

   dig -x <IP> @<pdns_ip> +short

   CODE
    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;' "

*************************** 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)

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:

*************************** 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

If you have problems configuring the integration:

1. Disable the dnsproxy service:

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

   CODE
    Where

   <token> — authorization token

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

2. 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;' "

   CODE
3. Reconfigure the integration.