mu [OT]: dyn_dns and router ip address

From: Dave Houghton (
Date: Sat Nov 16 2002 - 20:09:14 CET

Here's a little poser for hopefully better brains than mine.

I've set up a local private lan for use by Phd research students in my group:-
6 workstations + router with fixed ip via the Astrophysics dept private lan/internet router.
Port forwarding set up on both routers, web,mail and db servers visible from internal net and internet.

Problem is when the Astrophysics router internet ip changes (assigned via dhcp).
In order to update my dyn_dns account to reflect the changed ip, I need to know what it is obviously.
I've got no physical or electronic access to the Astro router to get its ip and if run on the local net the
dyn_dns client script point the dns server to the internal ip address which is obviously incorrect.

The best I can come up with is :-

wget -q -O - | grep '[0-9]\{1,3\}\.' | tr -d [:space:] >ip

where getip.shtml contains


<title> Get Your IP Number</title>

<!--#echo var="REMOTE_ADDR" -->


which basically echos your internet ip back to you.

Can anyone come up with a better idea that doesn't rely on a third party server to be reliably up an running
24/7 ??

Dave H

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