Ubuntu: Wired connection not working



Question:

I am using a Acer Aspire One. Here is the Ubuntu Wiki Page about my computer.

I have a working wireless connection however when I plug a cat5 (Ethernet) cable in the lights flicker on the computer, but then nothing happens.

Output of iconfig:

eth0      Link encap:Ethernet  HWaddr 00:1e:68:96:1a:6b              inet6 addr: fe80::21e:68ff:fe96:1a6b/64 Scope:Link            UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1            RX packets:43 errors:0 dropped:0 overruns:0 frame:0            TX packets:12 errors:0 dropped:0 overruns:0 carrier:0            collisions:0 txqueuelen:1000             RX bytes:2622 (2.6 KB)  TX bytes:936 (936.0 B)            Interrupt:28 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:8 errors:0 dropped:0 overruns:0 frame:0            TX packets:8 errors:0 dropped:0 overruns:0 carrier:0            collisions:0 txqueuelen:0             RX bytes:480 (480.0 B)  TX bytes:480 (480.0 B)    wlan0     Link encap:Ethernet  HWaddr 00:22:68:92:7f:36              inet addr:192.168.1.6  Bcast:192.168.1.255  Mask:255.255.255.0            inet6 addr: fe80::222:68ff:fe92:7f36/64 Scope:Link            UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1            RX packets:5702 errors:0 dropped:0 overruns:0 frame:0            TX packets:5284 errors:0 dropped:0 overruns:0 carrier:0            collisions:0 txqueuelen:1000             RX bytes:4117327 (4.1 MB)  TX bytes:936709 (936.7 KB)  

Any understanding of this output is greatly appreciated.


Solution:1

According to your ifconfig results, the ethernet connection is "UP", which means that it can definitely see your switch. Please detail what switch it's plugged into.

The most likely problem here is that the ethernet connection isn't connected to anything that can see the DHCP server. Try manually setting an IP address :

  1. Right click on the network manager applet and choose "Edit Connections..."
  2. In the "Wired" tab, click the "Add" button.
  3. Enter a Connection Name like "Manual Ethernet"
  4. Click on the IPv4 Settings tab.
  5. Change the "Method" to "Manual".
  6. Under "Addresses" click on "Add"
  7. Put 192.168.1.20 for Address. Put 255.255.255.0 for Netmask. Put 192.168.1.1 for Gateway (I'm assuming that this is the gateway - check it with netstat -rn | grep UG - it should be the address listed after 0.0.0.0.
  8. For nameserver, put 192.168.1.1 and 208.67.222.222 (the second address is openDNS, a free DNS server that anyone can use).
  9. Click on the "Add" button at the bottom.
  10. Now activate your newly created profile - left click on the network manager applet, then choose your newly created connection.

Now try pinging your gateway with ping 192.168.1.1. You should see something like this :

scaine@GroovyTosh:~$ ping 192.168.1.1  PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.  64 bytes from 192.168.1.1: icmp_req=1 ttl=255 time=0.378 ms  64 bytes from 192.168.1.1: icmp_req=2 ttl=255 time=0.358 ms  64 bytes from 192.168.1.1: icmp_req=3 ttl=255 time=0.546 ms  

If this works, you'll need to troubleshoot why your DHCP device isn't serving addresses to your ethernet connection.


Solution:2

See AspireOne community documentation for your specific model if there are known problems for this situation.

About ifconfig:

  • no inet addr: on eth0 - means there is no static or dynamic IP address assigned to this interface
  • RX bytes:2622 (2.6 KB) TX bytes:936 (936.0 B) - there is a connection ongoing, RX are received bytes and TX are transmitted bytes.

From wlan:

  • inet addr:192.168.1.6 - ipv4 IP address
  • Bcast:192.168.1.255 - broadcast address
  • Mask:255.255.255.0 - netmask address
  • inet6 addr: fe80::222:68ff:fe92:7f36/64 - ipv6 IP address

Also what network card does your computer have?

lspci | grep Ethernet


Solution:3

Just use the Network Manager applet to connect. The hardware appears to be working.


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