Atypical Gateway Configuration

Centinul · 07-29-2005, 07:26 PM

I have an interesting problem. I have a computer that has a wired ethernet card in it. Unfortunately I cannot run a wire from the wireless router to the PC. Additionally there are no PCI slots so a wireless card cannot be installed. I have another desktop w/ FC4 on it that has an onboard ethernet card and uses a wireless card to get access to the internet.

Here is the question:

Can I run the FC4 machine as a gateway behind a router so I can use the other machine to get on the internet?

Here is the configuration

Internet---------> Wireless Router ------------> FC4 Gateway Box -------> Box 4 Net

If this is possible how would I do it?

The FC4 Gateway Box has the 192.168.x.x IP address scheme.

This is the goal I have in mind. The reason why I want the "Box 4 Net" to have internet access is because it lacks a Cd-ROM or Floppy drive. I want to install Gentoo on it. In order to do this I need it to have access to the internet and to setup a FTP server on the "FC4 Gateway Box" so I can initiate the Gentoo Installation.

Please let me know if this is confusing or if there is another way I could do this.

The help is much appreciated.

Matir · 07-29-2005, 08:42 PM

Well, I'd be happy to get you installing Gentoo on a box!

Seriously, If I were you, I would look into "ethernet bridging" for your FC4 box. This will avoid needing it to be a gateway, and just allow the computers to all be part of the same "virtual LAN"

Centinul · 07-29-2005, 11:17 PM

Is it very hard and do you think it would allow me to install gentoo on the cdrom and floppyless box through the network?

Matir · 07-30-2005, 09:41 AM

If you can perform a cd-less install in gentoo, then I have no doubt that would work.

Centinul · 07-30-2005, 12:41 PM

To be honest I've never performed a CD install in Gentoo and I'm confused by the instructions. I don't understand how the machine that is receiving the install will receive the correct IP information off of the network boot.

The machine that would store the install runs FC4 while the machine that is looking for the install currently has Windows 2000.

Do you have any tips for success?

Centinul · 07-31-2005, 10:47 AM

Well I tried Ethernet Bridging and I couldn't get the machine I wanted to get the internet, also the machine that I setup the bridge on wouldn't get access to the internet.

Essentially this is the setup I'm aiming for

Internet-------------->Wireless Router----------> wlan0-->FC4 Box--- eth0---> MACHINE I WANT ON INTERNET

Where wlan0 is the interface that faces the internet and eth0 is the interface facing the machine I want on the internet.

I tried setting up a gateway also, but I couldn't get any activity on the eth0 interface. It was enabled and everything but when I looked on the back of my PC at the NIC there was no blinking lights or anything, also the computer connected to it said that the cable was unplugged. I tried multiple cables to rule out the possibility of a cable problem.

Can someone help me get the "MACHINE I WANT ON INTERNET" on the internet please? Also, just as a note that machine is running Windows 2000.

Matir · 07-31-2005, 12:11 PM

To connect the two network cards directly together, you'll need to make sure you are using a crossover cable.

Centinul · 07-31-2005, 02:39 PM

How come? It's just a gateway connection correct?

Matir · 07-31-2005, 03:13 PM

In order to make two network cards talk directly to each other, you need a crossover cable, regardless of what you are doing in software.

Centinul · 07-31-2005, 05:51 PM

Sorry i'm such a n00b

I thought I would atleast get some activity with a regular cable.

This would be much easier if this box had a CD-ROM

Matir · 07-31-2005, 06:31 PM

Yeah, it probably would. No chance of borrowing a CD-ROM from another machine?

About the cables... Ethernet uses 4 of the 8 pins in CAT5/RJ45. Each ethernet card has a receiver and a transmitter in it, each of which uses a pair of wires. With a straight-through cable, you get something like this:

Code:

TX ---------- TX
TX ---------- TX
RX ---------- RX
RX ---------- RX

Because of the crossover in a crossover cable, you get something more like this (sorry, couldn't draw diagnoals with ASCII art, had to rearrange pins)

Code:

TX ---------- RX
TX ---------- RX
RX ---------- TX
RX ---------- TX

Centinul · 07-31-2005, 06:48 PM

Well the problem with the PC is that it's a small form factor machine and it takes a slim cd-rom that just plugs into the PC, much like a laptop. I'm looking at one on e-bay but I wanted to figure out an alternative in the mean time. I guess I'll just have to wait until I get a CD-ROM and do a networkless install

Matir · 07-31-2005, 06:50 PM

If you can get a crossover cable and set up ethernet bridging (trivial, as I understand it), then you should be in business right now.

Matir · 07-31-2005, 06:54 PM

For a bit more detailed information on network bridging, check out http://wiki.linuxquestions.org/wiki/Bridging_made_easy

Centinul · 08-02-2005, 03:54 PM

Well I tried to setup a gateway but I'm having issues. My gateway box gets access to the internet fine but the windows 2000 box behind it can't get anything, can't even ping the gateway box.

I have my firewall configured like so:

Code:

iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE
echo "1" > /proc/sys/net/ipv4/ip_forward
iptables -A INPUT -m --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -m --state NEW -i ! wlan0 -j ACCEPT
iptables -A INPUT -p icmp -j ACCEPT
iptables -P INPUT DROP

when I do iptables -L the output reflects this code I put in.

For the internal side of the gateway box I have a cable running to the uplink side of a hub and I have the windows box plugged into that hub. There is an interesting problem though. The uplink port has a button that controls whether it is functioning as uplink or not. When I make it function as uplink the indicator lights go out on both the hub and the card on the gateway box, while if I turn off the uplink functionality the indicator lights will come on, on both the network card and the hub. I really think that is the root of my problem. I also tried another machine on a hub behind the gateway and it wouldn't work either.

for my setup eth0 = 192.1.168.50 <-- Internal NIC
which is what I have configured as the default gateway on the windows 2000 box.

I can't even ping the gateway box from the windows box.

What's going wrong?