setting up ddclient

Derek Broughton news at
Thu Nov 22 19:35:43 UTC 2007

Albert Charron wrote:

> Derek Broughton wrote:
>> Not _entirely_ unrelated I should think.  dhclient provides hooks for
>> things like ddclient to run as soon as an IP address is obtained, so Wade
>> would only see any sign that ddclient is doing anything at the same time
>> as dhclient is doing something...
> My server at home has a fixed ip behind my router. If my router receives
> a new DHCP address from my ISP, ddclient on the server will update my
> dyndns address the next time the daemon executes its check...
> What ddclient does is comparing the ip it has in cache with the one
> returned by dyndns' script (the ip returned by this script is the public
> address... the one the router is using on the Internet).

Maybe that's how yours is working - there's no reason you can't do that -
but I know when I briefly used ddclient, I was hooking into dhclient.

> So, this is why I stated that dhclient and ddclient are unrelated...
> Maybe I don't have the good information here and maybe ddclient will use
> dhclient to perform his check too, but as far as I know, ddclient have
> never set my dyndns ip to my internal address (even when my server was
> on DHCP)...

Indeed, because your internal address isn't the one that is known to the
Internet. But doesn't it simply make sense for the ddclient on your server
to act every time it is issued an IP?  There's no point to running every,
for instance, 15 minutes, if you know you can't have changed the IP in that

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