Intro
ddclient updates dynamic DNS entries for accounts on a wide range of
dynamic DNS services.

This is applicable to a wide range of use cases. It’s commonly used when
you have an IP address that changes regularly (e.g. on a residential
network), that you want to keep service pointing at (e.g. your domain
name).



Installation
See the GitHub README.



Configuration
ddclient has two primary means of configuration:

(Recommended) The ddclient.conf file, which defaults to 
/etc/ddclient/ddclient.conf.
Passing in arguments via the command line.

There are three key pieces to configuring ddclient:

General settings
Routers: where should ddclient find your IP? For example, 
ipify, or one of 20+ others.
Protocols: what should ddclient update when your IP changes? 
For example, DuckDNS, Cloudflare, or one of 30+ others.



Example
A typical configuration file looks like:
	# General config
daemon=300

# Router
usev4=webv4,webv4=ipify-ipv4

# Protocol
protocol=dyndns2
login=myUsername
password=myPassword
myhost.dyndns.org

With this config, executing ddclient would start a daemon that 
every 300 seconds would:

Get your IPv4 address from the ipify web service.
Login to your dyndns account with the given username and password,
and update the myhost.dyndns.org domain to your current IPv4 address.

You can set up ddclient to run on automatically using other packages on your
system, such as systemd, cron, dhclient, dhcpc and others. There are 
additional sample startup scripts in the GitHub repository.



Using environment variables
As of version 3.11.0_1, ddclient supports using environment variables inside the
configuration file. By appending ‘_env’ to a parameter, ddclient will interpret
the value of that parameter as the name of an environment variable and use the 
value of that environment variable as the configuration value. This allows to 
keep sensitive information such as the login or password outside of the 
configuration file.
	login_env=DDCLIENT_LOGIN
password_env=DDCLIENT_PASSWORD
myhost.dyndns.org

This example config file will use the value of the environment variables 
DDCLIENT_LOGIN and DDCLIENT_PASSWORD as the login and password for the 
domain myhost.dyndns.org respectively.



Command-line arguments
For simplicity, it’s recommended you use the ddclient.conf file over command 
line arguments. If you can’t use the default location, you can use the file 
argument only to read config from a different file, e.g. ddclient-file 
ddclientCustom.conf

However, any arguments can also be provided via the command line when invoking
ddclient. For example:
	ddclient -daemon 300 -protocol dyndns2 -login myUsername 
-password myPassword myhost.dyndns.org

ddclient prioritizes command line arguments, then falls back to ddclient.conf,
then falls back to in-built defaults.



Support
If you need extra help, want to report a bug, or submit a feature request, 
create a GitHub issue. Before posting, check it is not a duplicate and the 
problem is present on the latest version of ddclient.

If you want to contribute code to ddclient, raise a pull request on GitHub.