I installed ddclient with Synaptic in Ubuntu Karmic, and a GUI config dialogue came up. There were a couple of fields I didn't know about and left blank. One seemed to be asking for a port, with examples eth0 and ppp0. I have a DNS modem connected to a router.
It also asked for the complete dyndns domain, and the examples did not make any sense to me.
The config GUI is gone; please tell me what additional stuff I need to put in which file.