Thank you as well from me..I just joined the list two days a go and missed some
of the postings. I just bought the hub last week, got the linux machine
working, and had no idea of the implications. Thank you for reposting.
Lisa
On Sun, 16 Apr 2000, you wrote:
> :)
> Ok, I've seen the light, I'll be getting another network card.
> Thanks for all the thorough answers.
>
> On Sun, 16 Apr 2000, Stephen F. Bosch wrote:
> > I'm resubmitting this response in the interest of helping everybody set
> > up their private networks:
> >
> > David Nordlund wrote:
> > >
> > > Hi, I've got a system arrangement that goes something like this.
> > > I have computer A(Mandrake 7) and computer B(Corel 1) connected to a hub.
> > > Also connected to the hub is a cable modem, C. C is good friends with
> > > A, but isn't really on speaking terms with B.
> > > (The cable modem is set up for the MAC address in computer A)
> >
> > You should try resetting the cable modem (if it is a Motorola, there's a
> > reset tab on the back) while it is connected to the hub. It should
> > reacquaint itself with its new friend, the hub.
> >
> > Having said that, this is not a MAC address issue. I'm not surprised
> > you're having problems, you've made some bad assumptions (and I suspect
> > you're also making your cable ISP's network not very happy =) ).
> >
> > But I'm interrupting.
> >
> > > Each computer has one ethernet card. I can get A talking to B if
> > > I ifconfig eth0 to a private network IP (192.168.0.1) but then it won't
> > > talk to the cable. B won't talk to A if A is set to the IP address that
> > > the cable modem gives it(via DHCP).
> >
> > *argh*
> >
> > This is bad (you are sending garbage private IP packets out onto the
> > loop), and it won't work.
> >
> > Let's start from the beginning.
> >
> > Your cable ISP gives you *one* DHCP assigned IP address, and it passes
> > you this IP address through the cable device. The network hardware on
> > their end can be configured to pass multiple DHCP addresses to *one*
> > cable device, but you're not paying for this and you didn't get it. What
> > does this mean? You can only have *one* interface connected to the cable
> > modem. Based on the scenario you described above, you have two.
> >
> > Survey says?
> >
> > *BZZZZZZZZT*
> >
> > Item two: Let us assume that it's even *possible* for you to assign a
> > separate IP to B. Now you have put two machines which are on *different*
> > IP networks (one on 192.168.0.0 and one on 24.0.0.0) on the same
> > *physical* network. They will most definitely be ignoring each other,
> > you can count on that.
> >
> > Survey says?
> >
> > *BZZZZZZZZZT*
> >
> > Enough Family Feud references -- let's fix this.
> >
> > > Is it possible to get A & B talking to each other while A is on
> > > the net? If so, I assume I can masquarade B through A.
> >
> > Make sure you're clear about what masquerading is. In order to
> > masquerade, you need a gateway machine (essentially a router) between
> > your private network (192.168.0.0) and the public Internet (here in the
> > form of network 24.0.0.0). This means that your hub *cannot* be on the
> > public side! Only *gateway* devices can have a presence on the public
> > network.
> >
> > In masquerading, the gateway machine will rewrite all the packet headers
> > destined for the public network so that they have a valid, public IP
> > address on them (this is, in your case, the IP that is assigned to you
> > via DHCP), and will rewrite the returning packet headers with the
> > appropriate private IP address before sending them out onto the local
> > network.
> >
> > A possible scenario is this:
> >
> > Machine A has *two* (sorry) ethernet adapters, one *external* (we'll
> > call this eth0, which you connect to the cable modem) and one *internal*
> > (called eth1, which is connected to B using a crossover cable or
> > connected to the hub, in which case you can add as many other machines
> > as the hub will handle).
> >
> > Try to think in terms of interfaces. It is the interface that has the IP
> > address.
> >
> > So here, eth0 has the IP address (on network 24.0.0.0) assigned to it
> > via DHCP, and eth1 has a static address on the private network
> > 192.168.0.0. It's usually wise to use 192.168.0.1, it cuts down on
> > confusion. This is becomes the default gateway for the machines on your
> > private network. The gateway machine will then forward packets as
> > appropriate between the private and public networks, providing you have
> > IP forwarding enable and ipchains configured properly.
> >
> > The machines on your network (based on our example) can have any address
> > from 192.168.0.1 to 192.168.0.254. The terminating octets of 0 and 255
> > are reserved as network numbers and broadcast addresses respectively.
> >
> > So, to make a long answer short, yes, you will need an additional
> > network card -- but if you are going to set up IP masquerading, you have
> > some reading to do =).
> >
> > Start with the IPCHAINS how-to. You can find it at www.linuxdoc.org.
> >
> > -Stephen-
> >
