dsl_masquerading

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Subject: Re: DSL Connections on one NIC
From: RTS <rts@rdr.net>
Date: Mon, 20 Sep 1999 14:29:29 -0500


At 03:19 PM 9/20/99 -0500, you wrote:
>
>I am getting DSL installed, the modem that Bell Atlantic is giving me can
>plug into my NIC card or my hub.  I have a network at home running on
>privite IP's masquerading through my linux box.  Is it possible to have
>leave just one NIC card in my system and just plug the DSL modem into my
>hub and then just masquerade my other computer through the linux box, then
>back out through the hub on just one NIC, or would I need to put a second
>NIC in and put the DSL modem on one nic, and the network/hub on the other
>NIC.  
>
>Any pointer would be helpfull.

Connect your xDSL to one nic installed in the Linux Box.  Attach you hub to
the other nic.

This will keep you linux box as the gateway and masquerade everything
through it.

===

Subject: Re: DSL Connections on one NIC
From: Tony Coronado <TCoronado@creteseal.com>
Date: Mon, 20 Sep 1999 12:24:47 -0700


On Mon, 20 Sep 1999, Philip Jenkins wrote:
> I am getting DSL installed, the modem that Bell Atlantic is giving me can
> plug into my NIC card or my hub.  I have a network at home running on
> privite IP's masquerading through my linux box.  Is it possible to have
> leave just one NIC card in my system and just plug the DSL modem into my
> hub and then just masquerade my other computer through the linux box, then
> back out through the hub on just one NIC, or would I need to put a second
> NIC in and put the DSL modem on one nic, and the network/hub on the other
> NIC.  
> 

That is almost our exact configuration for the office.  Private IP's are
for the workstations.  The servers and dsl modem are all connected via
10/100BT switch.  Since the client workstations are not aware of the dsl modem,
they simply see the linux gateway, which in turn forwards all traffic to the
modem; the switch ensures that the dsl modem only sees traffic from the gateway

===

Subject: Re: DSL Connections on one NIC
From: "M. Neidorff" <neidorff@bellatlantic.net>
Date: Mon, 20 Sep 1999 18:28:28 -0400


At 03:19 PM 09/20/1999 -0500, you wrote:
>
>I am getting DSL installed, the modem that Bell Atlantic is giving me can
>plug into my NIC card or my hub.  I have a network at home running on
>privite IP's masquerading through my linux box.  Is it possible to have
>leave just one NIC card in my system and just plug the DSL modem into my
>hub and then just masquerade my other computer through the linux box, then
>back out through the hub on just one NIC, or would I need to put a second
>NIC in and put the DSL modem on one nic, and the network/hub on the other
>NIC.  

Bottom line as I see it...you need to have 2 nics in your linux box.  One
has the gateway ip address the other has the masq address.  I'm set up that
way and it works like a charm.

===

Subject: Re: DSL Connections on one NIC
From: Alan Mead <adm@ipat.com>
Date: Tue, 21 Sep 1999 10:10:14 -0500


At 09:45 AM 9/21/99 +1200, Juha Saarinen wrote:
>I'm running ADSL fine here with a single NIC in my Linux server, and the NTE
>hooked up to my switch. My NTE is a Nokia M10 router, so I just point my
>Linux box to it as the default gateway, and MASQ the rest of the machines

OK, but if you had a hub, you couldn't assign it a gateway address, right?
I think Philip needs a second NIC (or a router).

===

Subject: Re: DSL Connections on one NIC
From: "Juha Saarinen" <juha_saarinen@email.msn.com>
Date: Wed, 22 Sep 1999 08:20:48 +1200


> >I'm running ADSL fine here with a single NIC in my Linux server, and the
NTE
> >hooked up to my switch. My NTE is a Nokia M10 router, so I just point my
> >Linux box to it as the default gateway, and MASQ the rest of the machines
>
> OK, but if you had a hub, you couldn't assign it a gateway address, right?
> I think Philip needs a second NIC (or a router).

Why would I have to? The hub's there just to connect the PCs and the DSL
router. The DSL router is the gateway. If Philip has one of those evil ;->
DSL cards that don't do routing, well... that's when things would get
interesting. A dual-NIC set up might be called for in that case.

===

`Subject: Re: DSL Connections on one NIC
From: Jerry Winegarden <jbw@oit.duke.edu>
Date: Tue, 21 Sep 1999 19:44:38 -0400 (EDT)


On Mon, 20 Sep 1999, Philip Jenkins wrote:

> 
> I am getting DSL installed, the modem that Bell Atlantic is giving me can
> plug into my NIC card or my hub.  I have a network at home running on
> privite IP's masquerading through my linux box.  Is it possible to have
> leave just one NIC card in my system and just plug the DSL modem into my
> hub and then just masquerade my other computer through the linux box, then
> back out through the hub on just one NIC, or would I need to put a second
> NIC in and put the DSL modem on one nic, and the network/hub on the other
> NIC.  
There are been two types of answers to this question.
1) Yes, you need 2 NICs in your Linux box -let it be the gateway -
works great for me.

and

2) No, you only need 1 NIC in the Linux box - let the DSL modem
be "the gateway".

WHo is right?  They both are!	:-)

In man (most?) cases, the hardware that is installed by the phone company 
for DSL does NOT require you to have your own router - it's built into the 
DSL "Modem" (it's really more than just a modem).

Thus, you can just plug your DSL modem via 10-T cable into one port of your
LAN's 10-T hub and you've got it.  As they said, point to the DSL modem
as the gateway (it has an IP assigned to it).

This works IF the ISP you are using allows more than one machine on such
a connection.  You take a lot for granted with such an assumption:
GTE in Durham NC has ADSL and allows only one machine per ADSL line
IF you use GTE as the ISP.  However, using the exact same line, but
choosing Duke University as my ISP (which I can do if I'm at Duke),
I can have multiple machines.

Thus, in the case of most ADSL (non-Duke Univ) customers in Durham, they 
would need to have their own IP Masq router, which means that they would 
need to have 2 NIC cards in the linux box, with the LAN connected to one 
and the DSL modem connected to the other, running IPChains.

Thus, it depends on your ISP for DSL.  In a large number of cases, I
suspect the answer will be - no you don't need your own router.

However, you may still want your own firewall, in which case you would
use the linux box with 2 NICs.

Having your own router/masq has advantages and disadvantages.
If all you have is regular desktop boxes, probably not much difference
(other than security advantages of a firewall).  If you have servers
(e.g. web servers), then it is (slighly) more difficult to be behind the 
MASQ. 

===

Subject: Re: DSL Connections on one NIC
From: Philip Jenkins <pjenkins@uucom.com>
Date: Wed, 22 Sep 1999 08:53:40 -0500 (EST)


I only get one IP, so the rest of my computers have to masqerade out
through the main linux box.  From what you are saying is that if I have to
masqerade then I have to have the two nics? Right?

Thanks for all of your help!

===


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