[plug] Query about gateway computer settings

[Bret Busby]

On 24/03/2011, Jon L Miller <jlmiller at mmtnetworks.com.au> wrote:
> See below
>

> The LAN uses the IP address range 192.x.x.x, and a LAN (?) involving
> the gateway computer NIC that is interfaced to the modem, and a couple
> of computers, via a switch, and the ADSL modem, uses the 10.x.x.x IP
> address range.
>
> Jlm> so what you are saying is that you cannot ping the 10.x.x.x network
> from the 192.x.x.x network? If this is true you need to check your firewall
> and make sure you are routing packets from the 192.x.x.x to 10.x.x.x.
>

No.

The LAN NIC on the gateway computer, is IP adress 192.x.x.x, and the
NIC on the gateway computer, is IP address 10.x.x.x, and I can ping
both, successfully, from my workstation.

The ADSL modem is also IP address 10.x.x.x (different IP address, but
same range as the NIC that interfaces to it on the gateway computer),
and I cannot ping that from my workstation.

I do not have any firewall set up on the gateway computer.

The only firewall that exists, is one on the ADSL modem/router, if
that is set up, and I understand that the default setting for that, is
that it stops unsolicited packets from the Internet, and does not
restrict packets or requests from our side of the modem/router..

> The ADSL modem is set up for DHCP, and I found in the Admin Guide for
> the ADSL modem (the router one), a facility for reserving specified IP
> addresses, so that it is (to me) a bit like having static IP addresses
> within a DHCP facility.
>
>
> So, I have a reserved IP address for the NIC on the gateway computer,
> that interfaces with the modem, and I have that IP address specified
> as a static IP address in the NIC configuration of the gateway
> computer.
>
> I have got the gateway computer set up, so that I can go out on the
> Internet, via the ADSL modem/router, and I have used that to perform a
> system update on the gateway computer.
>
> On both NIC's on the gateway computer, I have the IP address of the
> ADSL modem, specified as the IP address of the DNS server (using
> System -> Network -> DNS).
>
> Jlm> why are you using the same ip address on both NIC's? If the gateway
> computer only has 2 nics, then one needs to be configured for internal LAN
> 192.x.x.x and connected to a switch or hub and the other for the external
> LAN 10.x.x.x and this is connected to the adsl modem.  Routing will need to
> be setup as a static route from the 192.x.x.x to 10.x.x.x.
>

I had stated that the two NIC's on the gateway computer, have
different IP addreses; the one interfaced to the LAN, has IP address
in the range 192.x.x.x, the same range as the LAN, and the one
interfaced to the ADSL modem/router, is in the range 10.x.x.x, the
same range as the ADSL modem/router.

It is the address for the DNS server, that is set the same for both NIC's

>
>
> On my workstation, I have tried using the IP address of the LAN NIC on
> the gateway computer, as the DNS server, and I have tried using the IP
> address of the NIC on the gateway computer, that interfaces to the
> ADSL modem, as the DNS server, and I have tried using the IP address
> of the ADSL modem, as the DNS server, but I cannot get to the modem
> (any of pinging the modem, or the web interface for the modem, or,
> going past the modem, out onto the Internet), from my workstation.
>
> Jlm> DNS services will depends on if you are exchanging information upstream
> or just within the local LAN.  If using just the local LAN the DNS server
> can and should reside on the 192.x.x.x ip space, whereas if the DNS data is
> being exchanged with an upstream DNS master server then the put the ip
> address of the DNS server on the 10.x.x.x network and do a NAT for 10.x.x.x
> to the ADSL modem.
>

-- 
Bret Busby
Armadale
West Australia
..............

"So once you do know what the question actually is,
 you'll know what the answer means."
- Deep Thought,
 Chapter 28 of Book 1 of
 "The Hitchhiker's Guide to the Galaxy:
 A Trilogy In Four Parts",
 written by Douglas Adams,
 published by Pan Books, 1992

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