Gentoo home router

MarcusXP · Posted: Sun Aug 17, 2008 8:47 pm Post subject: Gentoo home router

Hi guys,

I am trying to build a Gentoo router at home.
I've read he documentation available here: http://www.gentoo.org/doc/en/home-router-howto.xml , and I've done pretty much all the steps described.
I have my eth1 connected to the internet (takes the IP automatically) and eth0 is my LAN, which will have IP addresses allocated dynamically from my Gentoo box (I already done that, it is working).
So now I have eth1 taking IP by DHP from my cable modem/router, and eth0 is manually set to 192.168.0.1, and I am running DHCP server over eth0.
The last step would be to make NAT working..so the computers connected to the eth0 interface will have internet from my Gentoo box. This is where I am stuck.
Also, in this guide, I see some kernel options, but most of them I cannot find in my 2.6.25-r7 kernel..
In my case, do I need PPP support and all these other stuff, enabled in kernel ? If not, which ones to enable ?

Also, when setting up NAT by running the iptables commands, I get this error at the second command in that list:

Server ~ # iptables -t nat -F
iptables v1.4.0: can't initialize iptables table `nat': Table does not exist (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.

Thanks a lot,

This is the kernel config listed on the http://www.gentoo.org/doc/en/home-router-howto.xml

Xanadu · Posted: Sun Aug 17, 2008 10:06 pm Post subject:

MarcusXP · Posted: Sun Aug 17, 2008 10:37 pm Post subject:

Yep, I figured that out

I enabled everything it was in that table and I could find in kernel, I recompiled the kernel, reboot, and now I was able to run those commands.

However, I made a mistake, and I don't know how to undo ..

NeddySeagoon · Posted: Sun Aug 17, 2008 10:48 pm Post subject:

MarcusXP,

Is there a difference for you ?
-I means insert, with no position, at the top of the table
-A means append to the end of the table.

What does

MarcusXP · Posted: Sun Aug 17, 2008 11:02 pm Post subject:

MarcusXP · Posted: Sun Aug 17, 2008 11:09 pm Post subject:

I did everything in that tutorial.. but it doesn't seem to be working. From a computer connected to eth0, I cannot ping outside (yahoo.com for example). I can ping to my computer, but not outside.. so I didn't setup iptables properly, it seems.

Moreover, I think I have a problem with my ISP (or my home router or something) - when I plug some computers, internet stops working.. it is a random thing.. if I unplug the last computer from the network, internet comes back again.. maybe they have a limit of 4 or 5 computers in their routers ? My ISP is Bell (Canada) and I have a Linksys DSL modem/router.

MarcusXP · Posted: Sun Aug 17, 2008 11:14 pm Post subject:

My iptables rules..

NeddySeagoon · Posted: Sun Aug 17, 2008 11:18 pm Post subject:

MarcusXP,

I cheat. I use Smoothwall on a dedicated system for a home firewall so I don't play with iptables directly unless I need something odd.
Smoothwall is a network appliance - it takes over the system you install it on and thats all it does.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

MarcusXP · Posted: Sun Aug 17, 2008 11:24 pm Post subject:

Well I want to learn Gentoo, and this is one step..

Also, I noticed that when I plug the network cable in the second NIC (the "LAN" one, that I running DHCP over it, and I want to give internet to), my internet goes down right away.
I can ping my DSL modem/router, but I don't have internet anymore, and also no one connected to my DSL modem/router..
How can my modem/router "know" when I plugged a cable in another network card in my computer ? This is odd ...

NeddySeagoon · Posted: Sun Aug 17, 2008 11:36 pm Post subject:

MarcusXP,

Your ISP can detect your use of NAT but they probably don't bother.
Maybe your NAT is not set up properly and unrouteable packets with destination addresses in the 192.168.x.x range are being sent to your ISP.
Thats not supposed to happen and they will be dropped by your ISP, however, your ISP may choose to drop all your traffic while the unroutable packets appear.

To see whats happening on your interfaces you need tcpdump or one of its look alikes. This is a packet 'sniffer' it will capture all of the traffic on an interface of your choice, so you can see what is coming and going.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.