Will this work: three machines to one cable modem???

Will this work: three machines to one cable modem???

Post by Nebu John Matha » Mon, 02 Mar 1998 04:00:00



Just wondering whether this is possible:

equipment:
----------
Machine 1: has one ethernet card (linux machine)
Machine 2: has one ethernet card (winblows)
Machine 3: has one ethernet card (openbsd)
One eight port HUB
One cable modem

Can I hook the cable modem, Machine 1, 2 and 3 all to the hub and have
network where machine's 1,2,3 can all communicate with each other, and
also can connect through the cable modem to the net (simultaneously).
I'm just unsure of whether I need a server to receive the cable modem or
whether I can treat the cable modem (hooked to the net) as just another
piece of my network.

Thanks for your advice!
Nebu

 
 
 

Will this work: three machines to one cable modem???

Post by Jacek Trzebun » Mon, 02 Mar 1998 04:00:00


IP Masq... You cant assign 1 IP address to all 3 computers.  Also,
some cable companies will shut down your modem if it detects more than
one MAC, namely RoadRunner.

Quote:>Can I hook the cable modem, Machine 1, 2 and 3 all to the hub and have
>network where machine's 1,2,3 can all communicate with each other, and
>also can connect through the cable modem to the net (simultaneously).
>I'm just unsure of whether I need a server to receive the cable modem or
>whether I can treat the cable modem (hooked to the net) as just another
>piece of my network.


 
 
 

Will this work: three machines to one cable modem???

Post by Kevin Rodd » Mon, 02 Mar 1998 04:00:00


:Just wondering whether this is possible:
:
:equipment:
:----------
:Machine 1: has one ethernet card (linux machine)
:Machine 2: has one ethernet card (winblows)
:Machine 3: has one ethernet card (openbsd)
:One eight port HUB
:One cable modem
:
:Can I hook the cable modem, Machine 1, 2 and 3 all to the hub and have
:network where machine's 1,2,3 can all communicate with each other, and
:also can connect through the cable modem to the net (simultaneously).
:I'm just unsure of whether I need a server to receive the cable modem or
:whether I can treat the cable modem (hooked to the net) as just another
:piece of my network.

Add a 2nd Ethernet card to machine one... connect one to the modem and the
other to
the hub. See the Ethernet HOWTO for how to set up more than one card.

Then see the IP Masquerade mini-HOWTO.

Good Luck

Kevin Roddy
kroddyAThomeDOTcom

 
 
 

Will this work: three machines to one cable modem???

Post by Colin J. Stuckles » Tue, 03 Mar 1998 04:00:00



> Just wondering whether this is possible:

> equipment:
> ----------
> Machine 1: has one ethernet card (linux machine)
> Machine 2: has one ethernet card (winblows)
> Machine 3: has one ethernet card (openbsd)
> One eight port HUB
> One cable modem

> Can I hook the cable modem, Machine 1, 2 and 3 all to the hub and have
> network where machine's 1,2,3 can all communicate with each other, and
> also can connect through the cable modem to the net (simultaneously).

A cable modem is essentially a bridge. Some support bridging multiple
MAC addresses (eg. Bay LCW) and some support only a single address (eg.
Bay LCP).

If yours supports multiple MAC addresses, and your ISP will give you
multiple IP addresses (or you chose to steal them, in a non-DHCP
configuration) you can wire the cable modem to your hub and
get all three machines on the net with real IPs and no
masquaring (NAT) needed. You will probably need a crossover
cable to hook the cable modem to the hub, as the port is
wired in the assumption you are going to a NIC with a
regular CAT5 rj45 cable.

Otherwise, look into IP Masquarading as others have pointed out.

Best of Luck,

Colin Stuckless
Network Administrator

 
 
 

1. Three networks, one machine - Cable/ISDN/Private - ?

I'm attempting an unusual configuration; I'd like to know if this is
even -possible-.

I have a cable modem (xl0), an ISDN unit (tun0) and a local private network
(xl1)

The machine is a FreeBSD box. The FreeBSD box can receive packets from any
of the three interfaces.

I want outbound packets from the network to be directed via the cable modem
(xl0) UNLESS they are in response to a query via the ISDN (tun0) interface.

Can this be done? The only way I can think of to differentiate between tun0
and xl0 sourced packets is that each has a unique IP address. Is there a
link between the source and responding TCP/IP connection that could be
referenced by a routing daemon to respond via the appropriate interface?

Currently, all outbound traffic travels via xl0 - I can ping my system
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