Testing to find out if a cable or DSL modem is online or not

[John Macdonald]

On Fri, Apr 30, 2004 at 01:48:07PM -0400, Kerry Panchoo wrote:
> heres the current scenario:
> 
> within our application we see can see if one of our machines hast 
> checked in, we now have to determine the problem- it could be one of two 
> things:
> - The machine has stopped functioning
> - The internet at the location is down and the machine is still in 
> operation but cannot connect to our server
> 
> so we need to determine what the problem is. A ping with a pong only 
> tells you that the internet is fine and the machine is still in operation.
> 
> On the other hand a ping with no reply would not tell you where the 
> problem is. If i could determine if the cable modem is running, then i 
> know that our machine has gone down etc. If there is no response from 
> the cable modem then I know that there is an internet problem OR it may 
> be unplugged etc.
> 
> I did a search online and found stuff on how to DOS a cable modem haha; 
> not exactly what i was looking for.

A ping might do the job, actually - it depends upon
whether the "modem" is simply a datapipe (like
the grey Nortel boxes that Sympatico originally
was handing out) and something fancier that does
firewall, NAT, port forwarding, etc.  A fancier box
may be configurable to respond to ping rather than,
say, passing the ping through to the local computer
(or network).

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