eth1 not detecting link, despite NIC link light

I have a linux firewall which has a network card, eth1 that insists the link is down, despite having a link light on the card itself. I have used ethtool to check and the result is as follows:

There is a statically assigned ip address and the cable is definitely plugged into the NIC and the other end into the switch. There is even data activity light blinking, but linux still doesn't see the link.

So the link does not appear up, despite what the hardware says. The kernel definitely detects the card, otherwise there would be no eth1. I can ping the eth1 ip address from the box itself but not from anywhere else on the network, and nor can the box ping anything anywhere else.

It looks like it is not receiving any packets at all. I have changed switch ports, the cable, and used a second switch. Both switches have other devices working on them.

I have changed network cards, pci slots, rebooted several times etc.

This was working fine with the original network card and the ip address up until yesterday when there was a power failure and the machine went down hard. I am leaning towards broken hardware, but I've changed the NIC, the switch, the cable and used different pci slots. There is another network card in the box which still works... but I need two interfaces since it's a firewall.


I am truly stuck. Any ideas?

I use FreeBSD so my answer may have to be modified to suit Linux.
Run dmesg | more
Eth1 should be listed. If it is, see if Linux has the
ifconfig -u command or something similar
That will tell you if the interface is up. You may be able to run
ifconfig -u eth1.

on linux ifconfig -u is not recognized, but I suspect you mean the equivalent of "ifconfig up" to bring the interface up.

I had tried that of course, but the link is still detected as down even though I forced the interface up, which means it thinks that the cable is unplugged, but the link on the switch and the NIC both shows the link is active and even show some activity.

Are you sure that the static IP that you gave it is one the same subnet as the router?

I just looked back at your other posts and you don't even mention a router, you mentioned a switch. Show you setup as follows:
Modem > router if any > switch if any > PCs
Modify that to reflect your network.

Yes I am 100% positive the ip is correct. It has been using that ip for a month or two. It was working the day before the power cut.

Hmmm.. power cut..

Suspect hardware failure. Try the card in another setup or substitute with another.

If it had something to do with the power failure, something may have been damaged, not when the power stopped but when it started again. There may have been a power surge. Is your equipment connected through a surge protector?

I think that it is running off a ups so that should have buffered it, but I'm not sure.

I have tried a second network card and get the same thing with that card as well.

Did you try the second network card in a different slot? It's a long shot but it might work.

Yes I did. Still the same. I tried 2 cards in a different slot.

I think you've done everything possible on the config side. A power surge certainly could have fried something. If you have another machine that you could use for testing, move the HD to it just to see what happens.

thinking....... sounds like it isn't passing any packets, which says to me an iptables misconfiguration. Probably set to "drop all" somewhere..

I really don't like iptables...

http://lists.netfilter.org/pipermail/ne ... 42846.html

Check your cable, or just swap it with a different one. Just because you have a link light doesn't mean the cable is good. There's nothing wrong with your configuration, your card won't work until that says "Link detected: yes" which will only happen when the system detects some other device at the other end of the cable.

Yes I know that, but I have used 2 different cables and even 2 different switches, both of which have other hosts on them, and I still get the same result.

Janrocks: IPtables hasn't changed to my knowledge and even if it was blocking this, surely ethtool would say "link detected yes"?

do you get anything with:
dmesg | grep -i eth