Client -> Router -> Router -> WWW -- is this possib

[beejay]

I just ordered a notebook. Of course it will get a Gentoo-Installation. Now I want to do the following: My normal desktop PC is connected to the Internet via a router on eth0. It also has a second broadcom network-device onboard, that works perfectly (eth1). I want to connect my Notebook to eth1 of my desktop-pc and let this machine route the packets via its eth0 to the regular router (internet).

Is this supposed to work, and if yes, what do I need? (Never done this before)

Thanks in Advance
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[madchaz]

can it be done? yes

it's a bit complex for nothing, but you can do it
just remember that your PC will have to be on for your laptop
to be able to access the internet. also, if you didn't compile it in, you will need to add iptables support into your kernel

another thing to watch for is that your 2 subnets cannot be in the same
range. so let's say the "real" router's address is 192.168.0.1 and your pc's eth0 is 192.168.0.2. you will have to use another subnet then 192.168.0.0/24 for eth1

you could use 10.0.0.0 or 192.168.1.0/24

once you have made sure you have iptables avalable in your kernel, you need to emerge iptables

you will then have to make some simple rules to forward packets from eth1 to eth0 doing NAT

it'll work, but considering you can get a 4port hub for around 30$ now a days, maybe not worth it. your call, of course
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[Diezel]

It's not that har at all...There are alot of good IPTable scripts out there wich you can modify for yourself. I myself run kind of the same thing. Except I have 4 computers behind my server.
So go ahead...If for nothing else you'll learn IPTabels scripting
And that can't be all to bad, right?
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[pavera]

Well, I have a good reason for doing this.
I have the following setup:


ISP------Cisco1----subnet 1---Gentoo Firewall

-------------------------------subnet 2 |
|
Cisco2---------Public IP's
|
|----------Private IPs

I have a large subnet of public IP's that Cisco2 sees through 1 interface,
he also sees a private subnet through a second interface, that he nats out his third interface this interface is connected to the gentoo firewall, which in turn is connected to Cisco1 which handles my t1 connection to my isp... now, subnet 1 and subnet 2 are subnets that I have created out of my public IP's, so eth0 and eth1 on the gentoo box are in different subnets, I do not want to do any NAT whatsoever on the gentoo box, only monitoring, and QoS, the reason I don't want any NAT, is that the public IP's behind Cisco2 need to be completely accessible from the internet and I don't want to maintain 256 static nat translations, now I can see them from the Gentoo box, I can ping through cisco 2 to get to the public IP's back there, I can ping from the public IP's and private IP's to the inside interface of the gentoo box...

I can also ping from the gentoo box out to the internet, however I cannot for the life of me get the correct IP tables rules in place to get eth0 and eth1 on the Gentoo box to forward traffic back and forth between themselves freely. (I know I should probably be using a bridge type solution here, but I tried for a week and couldn't get that working, so today I threw this much of the solution together and couldn't get any farther...) Is there any way to do this with ip tables without doing any NAT translations (IE, when a connection is made to a public IP behind Cisco 2, the client out on the internet puts in the IP of that box, not the IP of the gentoo box, and when a public IP behind Cisco 2 connects to a server on the internet, the server sees the real public IP of the client, and not the IP of the Gentoo box)? I'd imagine this has to be possible, I basically just want the gentoo box to act like a router, but its got more software on it (IDS, traffic graphing, and I'm going to put some QoS on it, once I get connectivity established)

Any help with this would be greatly appreciated. Thanks.