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I am running an old Dell Inspiron 1521 built in 2007. I ran 11.10 on it and now have been running 12.04 LTS since its launch. When I first installed, I had to run modprobe b43 on the Broadcom Minicard DW1490 card installed in the machine. Upon the upgrade on or about 26 January 2013, I lost all network connectivity whether connected to a cable through the LAN or wireless.

$ less /etc/network/interfaces
auto lo
iface lo inet loopback

When I open my Network Tools, I get that the only Network device available is the Loopback interface (lo).

I really don't want to have to install an OS again just to get access to the network devices just so I can turn around and run it again to re-install Ubuntu up to current.

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1 Answer

If you want to use ethernet configured by system, just put following lines in /etc/network/interfaces

auto lo eth0
#auto lo
iface lo inet loopback
iface eth0 inet dhcp

Then your eth0 card should retrieve informatins from DHCP and you are connected.

Otherwise, please post output from ifconfig -a.

There you should see something like:

eth0      Link encap:Ethernet  HWaddr 00:9c:02:17:0b:f0  
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:20 Memory:d4500000-d4520000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:8166 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8166 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:2934406 (2.9 MB)  TX bytes:2934406 (2.9 MB)

wlan0     Link encap:Ethernet  HWaddr 10:0b:a9:7a:df:34  
          inet addr:10.0.0.2  Bcast:10.0.0.255  Mask:255.255.255.0
          inet6 addr: fe80::120b:a9ff:fe7a:df34/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:12048 errors:0 dropped:0 overruns:0 frame:0
          TX packets:10278 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:9967535 (9.9 MB)  TX bytes:4020027 (4.0 MB)

Hope this helps. PS.: if your output shows not eth0, but eth1 write

auto lo eth1
#auto lo
iface lo inet loopback
iface eth1 inet dhcp
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