ping questions

Karl Auer kauer at
Tue Dec 22 10:56:57 UTC 2015

On Tue, 2015-12-22 at 09:39 +0100, robert wrote:
> At work I have an internet connection with a static IP. A Zyxel isdn 
> modem is connected to it. Trying to ping that IP from outside fails (100% loss).
> When I am logged in a pc in a private network behind the modem, I can 
> ping the that same IP without loss.
> Why is that so?

It sounds a bit as if you have a PPPoE client running on your PC
handling the connection, and the "modem" really is a modem - not a

You can find out pretty quickly. Run this command in a terminal window:

   ifconfig | grep "a.b.c.d"

... where a.b.c.d is your static IP address.

If you see any output from that command, then your PC, and not the
modem, is handling the connection.

You said you have a "private network behind the modem". Do you have more
than one device (PC, printer, whatever) in that network?

Regards, K.

Karl Auer (kauer at

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