Can't get an IP address

Question

I'm running Ubuntu 9.04.

I have an onboard network card. The computer usually boots perfectly, but today, I don't have an IP address. The light is on, on the network card as well as the switch. Other computers work in the switch and I tried other ports to no avail.

# sudo ifconfig eth0 up
SIOCSIFFFLAGS: Resource temporarily unavailable
# sudo dhclient
... some messages ...
receive_packet failed on eth0: Network is down

Driver is e100. I tried modprobe eepro100, but still same problem.

Update: Putting in another network card didn't help! Could it be some sort of IRQ conflict?

Answer 1

The first thing to try is to make sure you have link. You can check this using either

# ethtool eth0

or

# mii-tool eth0

Look for a line about Link Detected. If it says no, then you have a problem with your network card, network cable or switch.

I wrote a guide to troubleshooting network problems that you might find useful.

Answer 2

have you tried a different network cable?

Answer 3

Set a static ip adress in /etc/network/interfaces

Something like this, change it to your network config

# The primary network interface
auto eth0
iface eth0 inet static
        address 192.168.0.100
        netmask 255.255.255.0
        network 192.168.0.0
        broadcast 192.168.0.255
        gateway 192.168.0.5

Then reboot router or other end of your network (computer - router/modem).

Now see what happens. Of still no succes, see if you can set iface eth0 inet DHCP instead of the above...