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# Gandi Dynamic DNS
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Cron job to auto update DNS records when WAN IP changes using Gandi Live DNS API on Debian GNU/Linux
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(This is obviously for a domain hosted by [Gandi.net ](https://www.gandi.net/ ))
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## Requirements
+ Debian GNU/Linux 10 (Buster)
+ curl : `apt-get install curl`
+ dig : `apt-get install dnsutils`
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## Install
Fetch script from git repo, install and configure
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```
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
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```
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nano /etc/live-dns/live-dns.conf
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```
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## How it works
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### /etc/cron.d/live-dns-update
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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.
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### /etc/live-dns/live-dns.conf
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Configuration file for the check/update script.
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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
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+ APIKEY="Your-API-Key" : Replace with you API key generated in security section of your profile on Gandi web interface.
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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
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### /usr/local/bin/live-dns-update.sh
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This is the script that is called by the cron job.
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+ 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
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Information logs are written to the system log `/var/log/syslog` .
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For Example :
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```
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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
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```
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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
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