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Re: Simple Linux to Linux(Debian) email

On Tue, Apr 09, 2019 at 02:34:30AM +0200, Jan Claeys wrote:
> On Mon, 2019-04-08 at 21:33 +0900, Mark Fletcher wrote:
> > I've created a very simple script that is capable of parsing the
> > output of "ip addr" and comparing the returned ip address for the
> > relevant interface to a stored ip address, and thus being able to
> > tell if the IP address has changed. What I'd like to do now is make a
> > means for the LFS box to be able to notify me of the fact that the
> > external-facing IP address has changed. 
> Why not use a dynamic DNS provider?
Primarily because it wouldn't solve my problem. IIUC it would allow me 
to map a domain name to the IP address assigned to my home internet 
connection. That means that when the IP address assigned to my internet 
connection changes, I can simply alter the mapping and my VPN clients 
start working again, without any configuration change on them. Great, 
but that isn't the problem. The problem is how I know that the IP 
address has changed and hence the DNS mapping needs updating. I don't 
see any way that a dynamic DNS service is going to know when my ISP 
arbitrarily re-assigns my IP. I need the machine that is being assigned 
the IP address to be able to tell me when it changes, and that is what 
this thread was about (specifically the "how it would be able to tell 
me" -- I'd figured out the "how it would know" for myself).

But thanks for trying to help anyway!