No internet connection, ifconfig shows errors

Question

I'veen using ubuntu for long time now but lately facing a new problem with the network adapter. I am not able to connect to the internet. After searching the Internet for a while, I found out that my network card is not receiving any packets.

Output from ifconfig:

root@sundar-Ubuntu:/etc# ifconfig 
eth0 
Link encap:Ethernet HWaddr 82:4d:41:2a:3d:aa
inet6 addr: fe80::804d:41ff:fe2a:3daa/64 Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1

RX packets:0 errors:82169 dropped:0 overruns:0 frame:82169

TX packets:29 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000 
RX bytes:0 (0.0 B) TX bytes:8380 (8.3 KB)
Interrupt:42 Base address:0xe000 

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:16436 Metric:1
RX packets:140 errors:0 dropped:0 overruns:0 frame:0
TX packets:140 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0 
RX bytes:11088 (11.0 KB) TX bytes:11088 (11.0 KB)

Any suggestions?

Answer 1

I see no IPv4 address assigned to your eth0 interface - which often is caused by some DHCP malfunction. Try running

sudo dhclient

and see if it fixes the problem. Normal output of ifconfig should look like

eth1  Link encap:Ethernet  HWaddr 00:22:15:7c:84:18  
      inet addr:10.1.1.4  Bcast:10.1.1.255  Mask:255.255.255.0
      inet6 addr: fe80::222:15ff:fe7c:8418/64 Scope:Link
      UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
      RX packets:696011 errors:0 dropped:0 overruns:0 frame:0
      TX packets:524673 errors:0 dropped:0 overruns:0 carrier:13
      collisions:0 txqueuelen:1000 
      RX bytes:861213542 (861.2 MB)  TX bytes:63705140 (63.7 MB)
      Interrupt:46 

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:16436  Metric:1
      RX packets:77511 errors:0 dropped:0 overruns:0 frame:0
      TX packets:77511 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:0 
      RX bytes:71573206 (71.5 MB)  TX bytes:71573206 (71.5 MB)

Answer 2

In my case, sudo dhclient did not fix the issue, at least right away. I rebooted and toggled the 'Enable Onboard LAN' setting from the BIOS. Then ethernet worked again for me.