dns-update

Automatically update DNS A-records in DirectAdmin to the UniFi UDM-Pro's dynamic WAN address without external services.

The dynamic WAN address is obtained via the UniFi's controller API and compared with the nameserver A-record value. Only if the values do not match the DNS A-record is updated via the DirectAdmin's API. Make sure that the DNS TTL (Time To Live) of the A-record is short (e.g., TTL=60) to minimize lagging cache when your ip address is changed.

Preparation

Configure the UniFi controller and DirectAdmin accordingly. All related variables should either be defined as shell (environment) variables or provided in a configuration file.

UniFi controller

Create a local user for the UniFi controller with read-only access.

Add user
Set role to Limited Admin
Set account type to Local Access Only
Complete the first name, last name, local username and local password fields. All other fields can be left blank.
In application permission, set the Unifi Network to View Only. All other applications can either be View Only or None.

Add the UniFi Controller variables to your shell or the configuration file.

# UniFi controller configuration
UI_ADDRESS = https://url_or_ip_of_your_controller
UI_USERNAME = '...'
UI_PASSWORD = '...'
UI_SITENAME = default

DirectAdmin

Create a DirectAdmin api-only login key.

Login to DirectAdmin
Go to password management > Login Keys (/user/login-keys)
Create a new login key

Type = key
Name = dnsupdate
Value =your own key or generate a random key by clicking the dices (don't forget to copy the value!)
Expires = never
Clear = unchecked
HTM = unchecked
Commands =
- CMD_API_DNS_CONTROL
- CMD_API_LOGIN_TEST
Password = your DirectAdmin password

Add the DirectAdmin variables to your shell or the configuration file.

# DirectAdmin configuration
DA_ADDRESS    = https://root_url_to_your_directadmin
DA_USERNAME   = username
DA_LOGINKEY   = SOMETHING_VERY_LONG
DA_DOMAIN     = example.com
DA_RECORD     = sub
DA_NAMESERVER = optional nameserver to query

Usage

Execute the script with a configuration file

bash dns-update.sh /path/to/your/dns-update.conf

Missing variables from the configuration file are assumed to be set in your shell (locally or as enviroment variables).

DA_DOMAIN=example.com; DA_RECORD=sub; bash dns-update.sh /path/to/your/dns-update.conf

If no configuration is provided all variables should be set.

Automatic trigger via Crontab

Trigger the DNS A-record update every 5-minutes using crontab (sudo crontab -e) and log the output in syslog.

*/5 * * * * /home/user/dns-update.sh /home/user/my-dns-update.conf 2>&1 | /usr/bin/logger -t my-dns-update

Make sure that the correct path to both the script and configuration are set.

Scan the syslog output

cat /var/log/syslog | grep my-dns-update

Multiple DNS records can be updated via separate configuration files (and crontab rules).

psmsmets / dns-update