Paul Burry and Others
ddclient is a Perl update client that will update dynamic DNS entries. It is a small and full-featured (including HTTPS support) requiring no additional modules. It has been reported to run on most *nix distros. Supported features include: operating as a daemon, manual and automatic updates, static and dynamic updates, optimized updates for multiple addresses, MX, wildcards, abuse avoidance, retrying failed updates, and sending update status to syslog and through email.
Lightweight, free and open-source client for Linux/Solaris/OpenBSD/Windows/Mac (no need for Perl, Python…), without bells and whistles (just command line). Runs as a service/daemon or as a console application, maintains multiple hostnames with the same IP address, web based IP detection (runs well behind a NAT router), is written in portable ANSI C source code with a little OS abstraction layer. Can be run under Windows or Mac OS X.