Dynamic DNS

For RFC2136 there is nsupdate(1) from bind. For dynamic DNS services there are several packages available, see #Update clients.

According to Wikipedia:

Dynamic DNS (DDNS or DynDNS) is a method of automatically updating a name server in the Domain Name System (DNS), often in real time, with the active DDNS configuration of its configured hostnames, addresses or other information.

The term is used to describe two different concepts. The first is "dynamic DNS updating" which refers to systems that are used to update traditional DNS records without manual editing. These mechanisms are explained in RFC 2136, and use the TSIG mechanism to provide security. The second kind of dynamic DNS permits lightweight and immediate updates often using an update client, which do not use the RFC2136 standard for updating DNS records. These clients provide a persistent addressing method for devices that change their location, configuration or IP address frequently.

Router

If the device needing DDNS sits behind a router, you should first check if the router itself can update any DDNS services. Although the selection of services may be limited, there are several advantages to using the router: it will probably be easier to set up, will require little to no maintenance, and will have no downtime (if the router is down you will not have Internet anyway).

Update clients

Note that some dynamic DNS providers do not require a dedicated client and can be updated with cURL.

Multi-service clients

• ddclient — Update dynamic DNS entries for accounts on many dynamic DNS services.

https://github.com/ddclient/ddclient || ddclient

• ddnsc — A simple & lightweight client written in python.

https://github.com/shyaminayesh/ddnsc || ddnsc^AUR

• inadyn — Dynamic DNS client with SSL/TLS support.

https://troglobit.com/projects/inadyn/ || inadyn

• inadyn-mt — A simple dynamic DNS client based on inadyn.

http://inadyn-mt.sourceforge.net/ || inadyn-mt^AUR

• ndyndns — Supports DynDNS and Namecheap.

https://github.com/niklata/ndyndns || ndyndns^AUR

Single-service clients

• duckdns — Update your DuckDNS.org entries from your computer with systemd.

https://www.duckdns.org/ || duckdns^AUR, duckdns-ipv6^AUR

• hetzner_ddns — Dynamic DNS daemon for Hetzner DNS

https://github.com/filiparag/hetzner_ddns || hetzner_ddns^AUR

• noip — Dynamic DNS Client Updater for no-ip.com services.

https://www.no-ip.com/downloads.php?page=linux || noip^AUR

• petrified — Bash client to update dynamic DNS at freedns.afraid.org.

https://gitlab.com/troyengel/petrified || petrified^AUR

ddclient

is compatible with many DDNS services and is the recommended tool for updating DDNS if your router is not an option. It includes systemd support.

After installing, edit the configuration file to set up your DDNS provider (it includes many examples). Then enable and start .

The configuration can be tested by running with the -noquiet and -debug options:

# ddclient -daemon=0 -noquiet -debug

Some of the compatible services are listed below, but you can also check the examples and protocols for more.

ddclient compatible services

Service	Configuration notes
Now-DNS	example
ChangeIP	example
Duck DNS	example
FreeDNS	example
No-IP	Use protocol , server
nsupdate.info	Use protocol
Dyn DNS	example
Namecheap	example
Dynu	example

Use an external website to determine IP address

If ddclient is unable to detect your IP address, you can configure ddclient to fetch your IP from an external webpage such as checkip.dyndns.org. This address is used by default when is specified. It is also recommended to increase the check interval to avoid frequent requests to the IP check service:

An alternative IP check service can be specified with the key:

Use a local script to determine IPv6 address

ddclient often gets the wrong IPv6 address or none at all, but instead of an external website the IPv6 address can be determined locally. This script can be used:

Tell ddclient to use the script:

/etc/ddclient/ddclient.conf

# obtain IP address from script
use=cmd,cmd='/usr/bin/get-ip'

Starting ddclient after networking is up

If you find that ddclient is unable to update your IP properly, it may be that the ddclient process is starting before networking is up. To fix it, you can edit the unit file to depend on network-online.target.

Other providers

Other DDNS providers are not compatible with ddclient so updating your IP with them may require a special tool or some custom scripting. Remember that if the service allows you to update your IP using the command line, you can automate the process using tools such as cron or systemd/Timers.