Dynamic DNS for gandi.net

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Settings.env	actually use it	2022-03-07 23:51:19 -07:00

README.md

DynGanDiNS

Dynamic DNS for gandi.net

How it works

curl external IP (from icanhazip.com by default)
curl to update the configured domain and record on Gandi via the API
Unless the IP has not changed (compared to previous check at /tmp/DynGanDiNS.ip)
Bash without the isms. Portability aimed.
systemd timer included!

How to use

Acquire an API key from Gandi by visiting your account page and finding the authorized apps UI to generate one. Then clone this repo locally. Update Settings.env with your API key, domain and record name. Then run make install (sudo as needed). After installation the environment variables are sourced from /etc/sysconfig/DynGanDiNS which will look like this (but hopefully with your info by now, not empty variables):

GDDNS_API_KEY=
GDDNS_DOMAIN=
GDDNS_RECORD_NAME=

If not using the systemd timer/service then you'll have to supply the environment variables some other way. Also probably don't bother with make install just use DynGanDiNS.sh how you please.

Also and optionally GDDNS_TTL is available for config and defaults to 3600 as well as GDDNS_EXTERNAL_IP which defaults to https://ipv4.icanhazip.com

Timer

By default the timer is configured to run the service every hour. Use systemctl edit DynGanDiNS.timer to override OnCalendar as desired.

# do this after having updated Settings.env and running `make install`
systemctl enable --now DynGanDiNS.timer

If this is the first time setting everything up you may want to run the service right away instead of waiting for the timer. Ensure it worked by checking journalctl -u DynGanDiNS.

systemctl start DynGanDiNS

If you already ran the install then the settings are here: /etc/sysconfig/DynGanDiNS

Why?

Internet service providers (ISPs) may or may not provide a static IP address for your connection to the World Wide Web. When they do not then it is dynamic which poses a problem for domain name resolution (DNS) trying to associate the name with an IP that might change. To work around this some way of getting the current IP address and telling the DNS about it is required—ideally exactly and only when the IP changes.

This problem is very common for home computers wanting to expose services behind DNS to the larger network. For example a Raspberry Pi hosting an artisinal handcrafted website about knitting and gardening. Or maybe a Wireguard VPN exposing an instance of Pi-hole for ad-block on the go! Or any other reason a server could be useful and you'd rather own instead of rent it.

It is highly likely that you will also need to forward the ports you'd like to use from your router to the computer running the service. This is because only the router talks to the internet—everything else routes through it! Usually traffic goes out but here we are handling traffic coming in. How to do this depends on your router and firmware, usually it's discoverable in the admin web GUI.

Security

Be diligent with firewall and SSH/access controls when connecting any computer to the internet! How to do this is outside the scope of this project...do your research and be careful!