Can't get an IP address

linux networking ifconfig eth0

16,755

Solution 1

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

# ethtool eth0

# 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.

Solution 2

have you tried a different network cable?

Solution 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...

16,755

Alex

I'm a Distinguished Engineer at Robinhood. I used to be the Tech Lead of Developer Productivity at Stripe where I built Sorbet. Before that I was the CTO and cofounder at Trimian. Before that I was a Software Engineer at Facebook on HHVM and the Open Graph. Before that I was the Tech Lead for Yahoo! SearchMonkey. See my homepage for more.

Updated on September 17, 2022

Comments

Alex almost 2 years
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?
- mas almost 15 years
  
  Are the the card's IP settings configured statically or dynamically (e.g. DHCP). If the latter, is the DHCP server up and configured and able to service the request from the client (e.g. spare IP addresses, MAC address table entry correct (if used) &c)?
- RateControl almost 15 years
  
  lspci command should so your card's make and model
- Alex almost 15 years
  
  DHCP. And other computers on the network are getting IPs fine. dhclient won't even get the packets out since the interface can't come up.
Alex almost 15 years

Link Detected : No. :(. Did something die in the motherboard to-do with networking?
John Gardeniers almost 15 years

Wouldn't be the first time. Disable the onboard card and plug in another one.