I run a server that is connected to several other boxes in a private network (192.168.0.0). I have had no problems previously, but upon a reinstall of Debian squeeze I have no connectivity to the private network: a ping of other addresses on that network fail. Ping and connection to outside world is fine. This box is configured similarly to another on this private network which connects successfully. I have quadruple-checked all my basic information. I post my ifconfig below of the malfunctioning device, then the ifconfig for equivalent nic on a box connected succesfully to the private network.

Questions:

1.Could it be a cable problem? (I don't see how since the cables have not been changed I do not believe since my reinstallation).

2. What about the difference in the last lines of eth1 below and eth2 of the successful box. Is it significant that the bad eth1 reads ...
Memory:fc3a0000-fc3c0000

while eth2 on the good box reads
Interrupt:16 Base address:0xef00



and on the good box:

Hi there,

It could be a cable problem. Did you try pinging the problematic machine from a working machine?

For the second point that you have raised. Please let us know the output of following commands:

1. lspci | grep net
2. cat /proc/interrupts

I suspect a routing problem, because you've got eth0 facing the public, and eth1 facing the internal network, and you're working just fine through the public interface. I suspect that works because the default route is pointing to the public interface.

Check your route table with the route command, and use route add if there's nothing there for the private network.

As SL00b suggested please show output of commands:
# ip r s
# ip a s
# netstat -rn

It turned out to be a cable problem. But these commands you all suggested will be very useful to me. They give me output I was looking for on this and on other problems.
Thanks again!

Glad, you got it sorted. Could you please mark this thread as solved.