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MasterPorky
Asked: 2014-07-15 15:45:38 +0800 CST

eth0 NO-CARRIER, ifconfig shows no IP address

  • 772

I left Ubuntu and came back after a while so I don't remember much. Now I'm trying to get my IP address. All I'm getting from running ifconfig is 

eth0      Link encap:Ethernet  HWaddr 3c:97:0e:11:22:0d  
          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:f2500000-f2520000

(BTW, I don't really understand what UP BROADCAST MULTICAST means.)

 $ sudo ifdown eth0 
 ifdown: interface eth0 not configured

Then 

$ sudo ifup eth0
Ignoring unknown interface eth0=eth0

And finally 2: 

$ ip addr show eth0
eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN   
group default qlen 1000 link/ether 3c:97:0e:11:22:0d brd ff:ff:ff:ff:ff:ff
ip

5 Answers

  1. A remote possibility for this issue can be a misconfigured Ethernet Interface.

    Use ethtool eth0 command to get the existing configuration.
    In some cases, you might find

    # ethtool eth0
Settings for eth0:
    ...
    Speed: Unknown!
    Duplex: Unknown! (255)
    ...

    If so, set the speed and duplex using:

    ethtool -s eth0 speed 100 duplex full

    For modern networks, this config should work.
    Once the speed and duplex are set, do dhclient eth0 if you still don't get an IP.

    Note: The above setup will reset on reboot. So, if the above solution solves your problem, add following lines to /etc/rc.local:

    ethtool -s eth0 speed 100 duplex full
dhclient eth0
    • 2

  2. Is this problem on a virtual machine? If so in the Advanced Network settings, on the Hypervisor see if the "cable connected" check box is ticked. It might just be that the VM isn't connected to the network

    • 1

  3. Try :

    ifdown eth0
ifup eth0
ip addr show eth0

    The meanings of UP, BROADCAST, and MULTICAST

    • UP - device is functioning
    • BROADCAST - device can send traffic to all hosts on the link
    • MULTICAST - device can perform and receive multicast packets

    More about mulicast visit Site

    • 0

  4. You might just try setting your IP address to something on your subnet. Assuming you're on a 192.168.1.255 network, try this:

    ifconfig address 192.168.1.50 netmask 255.255.255.0 gateway 192.168.1.1

    Replace 192.168.1.50 with the IP you want to get, and replace 192.168.1.1 with the IP address of your router/gateway.

    I have had a similar problem, and this solved it for me.

    • 0

  5. I have solved this problem by:

    1. Copying ifcfg file which currently run
    2. Putting the correct ip number as you want with its subnet on the new one. For ex: ifcfg-eth0 to ifcfg-eth1.
    3. Restarting the desktop.

    It worked correctly for me.

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