computer networkers, please rise

Some notes:
Unless you are setting up box "b" to be a bridge, the interfaces should have
address's on different ip networks (according to your diagram). Make eth0
192.168.1.x 255.255.255.0 and eth1 192.168.2.x 255.255.255.0. In
/proc/sys/net/ipv4 there is a file called ip_forward. It should contain the
number "1" if you want your box to forward packets (ie, route). To do this
do the following: echo '1' > /proc/sys/net/ipv4/ip_forward

Now, box a should know how to NAT/Masq for the 192.168.2.x network as well
as the 192.168.1.x network. Also, on box A do a route to point the
192.168.2.x network through the ip address of the 192.168.1.x on box b.
That way box A knows how to get to box C. Confused yet?

-dallas

----- Original Message -----
From: "Eric" <swive@getnet.com>
To: <plug-discuss@lists.PLUG.phoenix.az.us>
Sent: Wednesday, December 19, 2001 8:57 PM
Subject: computer networkers, please rise


> Hi,
>
> I'm gettin' jiggy with my home network, and I am getting myself wrapped
> around the axle. Can you help? I'll make this as short as possible,
> consistent with giving all necessary info:
>
> I have the following setup at home:
>
>
> LAN WAN
>
> [HOST_C
>
(192.168.0.3/24)]--------------[HUB]------------[HOST_A_(192.168.0.1/24)(wit
> h_DSL_CONNECTION)]-------------QWORST
>
>
>
>
> Between HOST_C and the HUB, I want to insert HOST_B. At some point
> hopefully, HOST_B will be a firewall; hence I need to get it to forward
some
> packets which is what I am testing now. HOST_B's name is "Lappy" and it
is
> a RedHat 7.1 Laptop with two PCMCIA slots, into which I have put two 3C59x
> cards. I know how to configure an eth device. To get this setup here to
> work, it seems as though I should just do it twice and then enable packet
> forwarding; is this correct? That is what I tried initially, but it was
all
> down hill from there.
>
> When I insert HOST_B between HOST_C and HUB, several different problems
> arise. Basically, instead of telling all the configurations/scenarios I
> tried, it boils down to the fact that if I keep all hosts on 192.168.0.0,
> either HOST_C can ping HOST_B and vice versa, but HOST_B cannot access the
> Internet, *or* HOST_B can access the Internet, but HOST_C and HOST_B
cannot
> ping each other. A few times, I managed to get it so neither alternative
> worked. Sometimes, in order to get functionality on eth0, I would have to
> unplug eth1, etc. It seems like HOST_B gets confused when dealing with
two
> NIC's with a hosts on each side, and can only figure it out when one
"side"
> is removed from the picture.
>
> Alternatively, I tried making both HOST_C and eth0 on HOST_B be on their
own
> network (10.0.0.0), while keeping eth1 of HOST_B and HOST_A on
192.168.0.0,
> but it just got worse. I can provide details if necessary, but there are
so
> many different combinations that my head is spinning.
>
> Let me say that I have enabled forwarding, and between HOST_C and HOST_B,
I
> was using a crossover cable, but between HOST_B and HUB, I was using a
patch
> cable. I have tested both of my PCMCIA slots, both my 3com cards, and
> cables--all seems to work. I have rebooted at least 35 times today
messing
> with this and that, and I feel nauseous. I haven't felt this bad since
the
> last episode of Emeril.
>
> Could anyone start by telling me whether I should have two networks
10.0.0.0
> & 192.168.0.0, or keep everything on 192.168.0.0? Next, do I put two
> entries in /etc/hosts, one for Lappy 10.0.0.1 and another for Lappy
> 192.168.0.1? I don't know what else; can anyone help?
>
> Eric
>
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