# Gandi Dynamic DNS Cron job to auto update DNS records when WAN IP changes using Gandi Live DNS API on Debian GNU/Linux (This is obviously for a domain hosted by [Gandi.net](https://www.gandi.net/)) ## Requirements + Debian GNU/Linux 10 (Buster) + curl : `apt-get install curl` + dig : `apt-get install dnsutils` ## Install Fetch script from git repo, install and configure ``` git clone https://gitlab.com/lab.8916100448256/gandi-dynamic-dns.git ./gandi-dynamic-dns cd ./gandi-dynamic-dns sudo bash ./install.sh ``` Then configure DNS record info and API key in file /etc/live-dns/live-dns.conf ``` nano /etc/live-dns/live-dns.conf ``` ## How it works ### /etc/cron.d/live-dns-update Cron job definition to check for WAN IP change and call Live DNS API to update the DNS record if necessary. By default runs the check/update script 2 times per hour, at every hour past 12 and 42 minutes. ### /etc/live-dns/live-dns.conf Configuration file for the check/update script. Needs to contains 3 environment variable definitions + DOMAIN="domain.tld" : Replace domain.tld with your domain name + RECORD="host" : Replace host with the sub domain you want to update when WAN IP changes + APIKEY="Your-API-Key" : Replace with you API key generated on the Gandi web interface. Check this page if you don't know the APIKey of your Gandi account : https://docs.gandi.net/en/domain_names/advanced_users/api.html ### /usr/local/bin/live-dns-update.sh This is the script that is called by the cron job. + First the WAN (external) IPV4 and IPV6 adresses are determined using http://me.gandi.net through curl + Then they are compared to the A and AAAA DNS records retrieved through dig for the configured host and domain. + In case of mismatch Gandi live DNS API is called to update the DNS records through curl using the configured APIKey Information logs are written to the system log `/var/log/syslog`. For Example : ``` December 12 12:42:02 passerelle root: WAN IPv4 : 1.2.3.4 December 12 12:42:02 passerelle root: WAN IPv6 : 1111:2222:3333:4444:5555:6666:7777:8888 December 12 12:42:02 passerelle root: DNS IPv4 : 1.2.3.4 December 12 12:42:02 passerelle root: DNS IPv6 : 1111:2222:3333:4444:5555:6666:7777:8888 December 12 12:42:02 passerelle root: No need to update IPv4 DNS record for sub.domain.tld December 12 12:42:02 passerelle root: No need to update IPv6 DNS record for sub.domain.tld ``` This script is based on the [mywanip.sh](https://github.com/Gandi/api-examples/blob/master/bash/livedns/mywanip.sh) sample provided by Gandi on their GitHub