IP forwarding stopped working after update [solved]

mariourk · Last edited by mariourk on Tue Apr 08, 2008 5:17 pm; edited 1 time in total

Hi,

I have a nasty problem, after I updated my router.
The router acts as a gateway for 2 networks. 192.168.1.x and 192.168.3.x.

The 192.168.1.x network is hooked to eth0. (I will call this network-A)
The 192.168.3.x network is hooked to eth3. (I will call this network-B)
An ADSL modem is hooked to eth1.
Eth2 is not used.

I tried to use eth2, instead of eth3, but that didn't fix anything.
Both ports are controlled by the same on-board network controller.

The funny thing is that forwarding for 192.168.1.x works fine. Network-A and the ADSL-modem
are both hooked to Intel gigabit network controllers. Network-B is hooked to an on-board Marvel
gigabit network controller. So, it is if eth2 and eth3 are broken. (ergo, the on-board controller
appears to be broken) However, they show up fine with ifconfig and I'm able to restart them any time I want.
Or even change IP's.

When I hook a laptop directly to eth3, with a crosscable, I'm still not able to ping.
I also tried to shutdown the firewall, but that didn't help either. So everything seems to
point to a broken controller. But is seems to function just fine

lspci output:

loisl · Posted: Tue Apr 08, 2008 11:26 am Post subject:

Hai,

what does Your /etc/sysctl.conf say?

Mine says

mariourk · Posted: Tue Apr 08, 2008 12:21 pm Post subject:

/etc/sysctl.conf doesn't have net.ipv4.ip_forward = 1.
However, I have echo 1 > /proc/sys/net/ipv4/ip_forward in /etc/conf.d/local.start
When I check it, it does work well:

Kosmas · Apprentice Joined: 14 Sep 2006 Posts: 280 Location: Greece

Hi mariourk,

First of all if I were you I would make sure that the hardware works ok. You can do that with 2-3 ways. On of the best way is to boot the live cd and check the connection with either the cross cable or use a switch/hub. Try to check all the interfaces with the same cable and see the results.

If you see that the hardware works ok, then maybe you should check other things like cables, switches etc. I think that if you get to the point that you have a correct physical connection you will get routing back up and running.

Hope I gave you a hint,
Kosmas.

mariourk · Posted: Tue Apr 08, 2008 1:13 pm Post subject:

Indeed. The livecd is a good idea to check the hardware
and rule out the software of the current system installation.
I had't thought of that, so thank you for that suggestion

I can't reboot that particular server right now. So I'll have to do that later.
In the meantime I've used an old FTP-server and rebuild that to a simple gateway.
I used that to route network-B through network-A. At least that give me some breath.
So now I can focus on a good solution :wink:

_________________
If there is one thing to learn from history, it's that we usualy don't learn anything from it, at all.

mariourk · Posted: Tue Apr 08, 2008 5:17 pm Post subject:

For some weird reason, the last system update caused the ports for eth2 and eth3 to swap.
So, eth2 became eth3 and eth3 became eth2. The is probably because the 2 ports are
controlled by a single controller. Anyway, all I had to do was plug the cable in the correct hole... :oops:

_________________
If there is one thing to learn from history, it's that we usualy don't learn anything from it, at all.