ping questions

Gene Heskett gheskett at wdtv.com
Tue Dec 22 13:44:44 UTC 2015


On Tuesday 22 December 2015 05:56:57 Karl Auer wrote:

> 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
> router.
>
> 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.
>
To me, the term "private network" means its behind a router doing a NAT.  
If the NAT is to a 192.168,x,y address, no router I am aware of will 
allow that to pass UNLESS that "port" is forwarded to a machine behind 
the router in which case that machine is free to respond or not 
according to how it is configured.

> --
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>~ Karl Auer (kauer at biplane.com.au)
> http://www.biplane.com.au/kauer
> http://twitter.com/kauer389
>
> GPG fingerprint: 3C41 82BE A9E7 99A1 B931 5AE7 7638 0147 2C3C 2AC4
> Old fingerprint: EC67 61E2 C2F6 EB55 884B E129 072B 0AF0 72AA 9882


Cheers, Gene Heskett
-- 
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