DDclient is a small but full featured Perl client used to update dynamic
DNS entries for accounts on Dynamic DNS Network Services free DNS service.
It has the capability to update more than only dyndns and it can fetch your
WAN-ipaddress in a few different ways.

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 e-mail.

This requires perl-IO-Socket-SSL to run.