Force Dyndns Updte as cronjob

[Guest]

[Mysterious]

Hi,

we´ve got a cable internet conenction which keeps it´s ip adress as long as your cable-modem isn´re disconnected. Dyndns expires it´s free account if you aren´t login one time a month. Now i´d like to add a forced dyndns update every month to prevent the expireing of my dnydns account. may someone can give me a hint how to do this as a cronjob? The forced update is already available at the gui.