Inadyn
Inadyn is an update client that keeps your IP address up to date at your DNS name provider.
But also if you have a free Host Service from dyn.com you can use the update client to update your account within every 30 days to prevent it from being deleted.
Just using the service is not sufficient to prevent your account from getting expired.
An update client prevents your account from becoming expired, and also makes sure a IP address change is updated for your host service.
More info about Inadyn can be found via: http://dyn.com/support/clients/linux/
For general update client information you can look here: http://dyn.com/support/clients/
It appears from the forum that it is not possible anymore to apply for a new free account. But on page http://dyn.com/legal/account-ownership-and-recovery-policy/ there is a reference that a new account can be created via https://account.dyn.com/entrance/ Just give it a try.
From 7-May-2014
From 7-May the free Dyn account will stop. See Dyn blog.
Since 14-May-2013
Starting now, if you would like to maintain your free Dyn account, you must log into your account once a month. Failure to do so will result in expiration and loss of your hostname. This activity helps us eliminate hostnames that are no longer needed and/or dormant. Note that using an update client will no longer suffice for this monthly login.
Dyn users should have a look at the following (german): http://www.ip-phone-forum.de/showthread.php?t=260356 and OpenDD
Creating a Feetz Image with Inadyn
Follow the directions from the /wiki/WikiStart.en# Wiki
After the following step you can configure the packages you want to have included in your image.
make menuconfig
Make sure the following is selected:
[*] Show advanced options
Package selection ---> Testing ---> [*] Inadyn-mt 02.24.36
Setup in Freetz web-interface
To update your account within the default 30 days you can use the parameter forced_update_period followed by the update period in seconds.
E.g. for one day you can use 86400 or for 10 days 864000.
If you have enabled the syslog you can verify the syslog messages. E.g. via a telnet or ssh connection you can using the following command:
logread
Or via the Freetz web interface: Status > Syslog You can filter on INADYN to show only Inadyn related messages. You will see that the every 10 minutes by default the IP address is verified for changes. Only if the IP address changed, your account at your DNS provider is updates with this new IP address.