In-a-dyn is a small and simple Dynamic DNS, DDNS, client with HTTPS support. It is commonly available in many GNU/Linux distributions, used in off-the-shelf routers and Internet gateways to automate the task of keeping your DNS record up to date with any IP address changes from your ISP. It can also be used in installations with redundant (backup) connections to the Internet.

Presentation here.


The configuration file on most systems is in /etc/inadyn.conf:

# In-A-Dyn v2.0 configuration file format
period = 300

# The FreeDNS username must be in lower case and
# the password (max 16 chars) is case sensitive
provider {
    username = lower-case-username
    password = case-sensitive-pwd
    hostname =

In-a-dyn comes with a systemd unit file, so simply restart the service or send SIGHUP to an already running inadyn to make it reload the .conf file. If you’ve built Inadyn yourself from source, the .conf file may be located elsewhere. See the --prefix argument to the configure script, use --help or see the README for details on building.

More examples in the inadyn.conf(5) man page and the README.


Issue tracker and GIT repository available at GitHub:

Origin & References

This is the continuation of the original INADYN project by Narcis Ilisei. The goal of this project is to focus on *BSD and various embedded Linux platforms, but Cygwin is also supported. All sane patches addressing this target audience are welcome!