updyn is a shell script that updates a dynamic DNS
service with the current IP address. It will work with any
dynamic DNS service that allows you to call a URL to
update the DNS. It works behind a router when an
external IP address is different from internal IP, optional
minimum time check, does not update unless your actual
IP is different from your assigned IP, and can be set to
update the DNS every set number of days whether or not
your IP has changed.