[from web site]
This is a simple Python script to register your dynamic IP address
using the NIC V2.0 protocol. We aim to be fully compliant with the
dyndns client specification. Starting with version 0.141, we use
https by default and will fall back to plain http if a timeout
occurs.

We currently support all options and latest recommendations by
Dyndns. Ipcheck is easy to install and very easy to use.

Root access is not required and no configuration files are needed.

Just specify your username, password and hostname(s) on the command
line (or cron entry).

You can specify the interface (default tun0) to search for your ip
address on or use web based IP detection.

There is also direct support for determining the IP address on the
following devices: Linksys (-L), Netgear (-N), Draytek (-D), Netopia
(-O), HawkingTech (-H), Cisco 667i (-C), Cisco 700 series (-I),
ZyXEL Prestige (-Z), SMC Barricade (-S)