Re: Cable modem

["Alan Mead" <amead8695 home com>]

When you say "gateway" you mean the IP address assigned by your cable
provider, right?

And when you say, "uplink port on my hub" you mean that you plugged the
cable modem into the uplink port of your hub and your other machines are
plugged into this hub as well, right?

If these guesses are wrong then please give us enough information so
guessing is not needed.

If I'm right then I have bad news:  I don't think this will work.  You could
try swapping the cable modem cable to a NON uplink port.  But I don't think
that will help; you've hooked all three computers to the Internet but you
only have 1 IP address.

But the good news is that it's easy to fix this with tools you may have
on-hand.  I have what I would call the "standard" basic setup for this
situation:  I have an old 486 "gateway" running a version of Linux called
LRP which can be found at www.linuxrouter.org.  Previously, I used Red Hat
on a newer machine for the same purpose.  This machine has 2 network cards.
One is plugged into the cable modem and the other is plugged into my hub (as
a normal slot).  My other computers are also plugged into the slot.  This
one computer is on both my LAN and the Internet.  The others are only on my
LAN.  All interfaces on my LAN (including the "internal" interface on my
gateway) are configured to be on the 192.168.0.x network with a netmask of
255.255.255.0.  My ISP's DNS servers are my DNS servers (although I also use
/etc/hosts so my local machines can access each other by name).  The
external interface of my gateway is configured according to my ISP's
specifications (static IP, netmask, etc.).  Both the Red Hat and LRP kernels
are configured to do IP Masquerading (also called Network Address
Translation or NAT) and I've made sure that several related kernel modules
are loaded (e.g., ip_ftp.o) by putting them in /etc/modules (I think
/etc/modules.conf or /etc/conf.modules on various versions of Red Hat).

And then it works.  The gateway keeps track of which internal machine is
talking to which external destination and performs some networking magic so
that all my machines can access the Internet at the same time and appear to
be a single machine to the Internet which receiving their individual data
streams.  There is a HOWTO and a fair amount of information about IP
Masquerainding available on-line.  There are a few network protocols that
will not work from behind these sorts of gateways... but not many.

So this probably only requires an additional network card and is needed if
you want to put multiple machines behind a single IP.  But there are many
other things that could also be wrong with the cable modem.  I would hook a
single machine directly into the cable modem.  I would use the Windows
machine because chances are good that they'll refused to help you, or be
genuinely unable to help, with Linux.  I would persistently pester Cox to
get that machine on-line.  Once you know it can be done and, ideally, know a
bit about how it was done, you can almost certainly get the gateway on-line
and servicing your LAN.

-Alan

PS - There are alternatives to having an actual computer running Linux...
you buy a combination hub/router/NAT gateway for only .. $120?  Conceivably
you even mean such a device when you say "hub" in which case your problem is
probably that you have configured your machine or machines with the ISP's
information rather than the router (the router is probably configured
through telnet or HTTP).

----- Original Message -----
From: "David Archer" <dmadance hotmail com>
To: <redhat-list redhat com>
Sent: Friday, August 24, 2001 11:12 PM
Subject: RE: Cable modem


> Well, the RF and LNK lights are solid, the TD and RD lights are
flickering.
> The light for the uplink port on my hub is flickering. I have 3 computers
on
> the hub. They can see each other, ie, you can ping them, ssh, get web
pages,
> etc. Try pinging the gateway and I get a Destination Host Unreachable
error.
> This is the same result for any other address out there. This is true of 2
> linux boxes. The third machine is a Windows box that was configured as I
was
> told. The Windows box can't see the internet as well. I tried commands
like
> dig yahoo.com, times out. I've read most of the cable modem Howtos and
have
> done everything that I can think of. Any suggestions anyone?
>
> thanks,
>
> David Archer
>
>
> >From: "Daniel L Quigley-Skillin" <dskillin home com>
> >Reply-To: redhat-list redhat com
> >To: <redhat-list redhat com>
> >Subject: RE: Cable modem
> >Date: Fri, 24 Aug 2001 18:06:34 -0400
> >
> >A good place to start...  What are the lights on your modem doing?  How
> >many
> >of them are there?  Are they labeled?
> >
> >D-
> >
> >-----Original Message-----
> >From: redhat-list-admin redhat com
> >[mailto:redhat-list-admin redhat com]On Behalf Of Brad Bonkoski
> >Sent: Friday, August 24, 2001 5:44 PM
> >To: redhat-list redhat com
> >Subject: Re: Cable modem
> >
> >
> >Well, I use cox cable, and other then the it (NOT BEING)"always-on". .
No
> >problems, of course their tech support folks read a script...
> >
> >There is a cable-modem howto on linux-doc.org
> >but you should be able to configure your Ethernet Card as if you were
> >sitting on a LAN.  Perhaps some further debuggin input would help resolve
> >your problem?
> >-Brad
> >
> >----- Original Message -----
> >From: "David Archer" <dmadance hotmail com>
> >To: <redhat-list redhat com>
> >Sent: Friday, August 24, 2001 2:40 PM
> >Subject: Cable modem
> >
> >
> > > I have just had installed a cable modem. I have had no luck using it.
I
> >have
> > > been given a static IP, and the modem is a Com21 modem. Any good
> >references
> > > or suggestions?
> > >
> > > I have done most of the obvious things, I set the gateway, DNS
servers,
> >ip
> > > of the NIC, and netmask to the values provided by COX cable. Nothing
> >works,
> > > and customer support from COX is worse than useless. Help!
> > >
> > > thanks,
> > >
> > > David Archer
> > >
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