[Techtalk] Destination Host Unreachable

[Malcolm Tredinnick]

On Sun, Mar 09, 2003 at 08:09:15PM -0800, Carla Schroder wrote:
> On Sunday 09 March 2003 7:44 pm, Arashi wrote:
> > Hi Jenny,
> >
> > I've checked my sister's network IP address and subnet (192.168.0.2
> > and 255.255.255.0 respectively), but I'm still getting "Destination
> > Host Unreachable" when I ping her computer.   I also  changed the
> > default gateway on my computer to 192.168.0.1 (this was confusing
> > because I read in some Google post that you find your default gateway
> > by using traceroute and looking at the IP address found on the first
> > hop) and made sure my sister's gateway was the same.  Is there
> > anything I else I should check?
[...]
> Make your gateways the same as the PC IPs. Machine A is assigned 192.168.0.1, 
> make the gateway 192.168.0.1. Machine B is 192.168.0.2, gateway 192.168.0.2

I'm sorry, but this is not correct. If Arashi's machine is going to
perform masquerading for her sister's machine (as is mentioned in a
later email), then her sister's box needs to have Arashi's machine as
the default gateway. Arashi's machine will have some upstream box (ISP's
address) as its default gateway.

The default gateway is the address to route things to that you don't
know about. The theory being that the gateway box knows how to route the
packets further and you can route directly to the gateway box (i.e. it
is on the same network as one of your interfaces).

Note that I am intentionally saying "default gateway" here, since you
can have multiple gateways specified (one for each of a number of
networks). But in the typical home network setup, you will generally
only have a single gateway box, which is often the one nearest the
modem.

Malcolm

-- 
I don't have a solution, but I admire your problem.