ethernet disconnected, shows up in ifconfig

9,150

Solution 1

Edit the interfaces file to remove

auto eth0
iface eth0 inet dhcp

Save and restart. Use Network manager to edit the connection and set it to automatically connect.

This command will open the interfaces file in Gedit with permission to save the file:

sudo gedit /etc/network/interfaces

I have both a wired and a wireless connection and all that is in my interfaces file is these two lines

auto lo
iface lo inet loopback

I have found from experience than anything else will prevent a connection and removing what is extra will solve the problem.

Solution 2

  1. Basic layer 1 ground check - is your ethernet port connected and are you sure the wire and modem port are fine? Please confirm that the ethernet port light blinks (either green or amber) when you connect the wire. Otherwise it is a physical layer issue. Does it work on other machines at the same swtich-port?

  2. Assuming the above is taken care of, Have you tried sudo ifconfig eth0 up?

  3. Also, check your /etc/network/interfaces file and see if the following line is there

    auto eth0

    This automatically enables eth0 on startup

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tekknolagi
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tekknolagi

Updated on September 18, 2022

Comments

  • tekknolagi
    tekknolagi about 1 year

    I am running 11.04, no remix. After installation, I could use wireless networks, but not ethernet. When I click on the connections menu item, it says

    Wired Network
    disconnected
    

    How do I fix this?

    Here is the ethernet portion of ifconfig:

    eth0      Link encap:Ethernet  HWaddr 00:16:36:86:f3:43  
          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:17
    

    And the result of lspci:

    00:00.0 Host bridge: Intel Corporation Mobile 945GM/PM/GMS, 943/940GML and 945GT Express Memory Controller Hub (rev 03)
    00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller (rev 03)
    00:02.1 Display controller: Intel Corporation Mobile 945GM/GMS/GME, 943/940GML Express Integrated Graphics Controller (rev 03)
    00:1b.0 Audio device: Intel Corporation N10/ICH 7 Family High Definition Audio Controller (rev 01)
    00:1c.0 PCI bridge: Intel Corporation N10/ICH 7 Family PCI Express Port 1 (rev 01)
    00:1d.0 USB Controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #1 (rev 01)
    00:1d.1 USB Controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #2 (rev 01)
    00:1d.2 USB Controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #3 (rev 01)
    00:1d.3 USB Controller: Intel Corporation N10/ICH 7 Family USB UHCI Controller #4 (rev 01)
    00:1d.7 USB Controller: Intel Corporation N10/ICH 7 Family USB2 EHCI Controller (rev 01)
    00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev e1)
    00:1f.0 ISA bridge: Intel Corporation 82801GBM (ICH7-M) LPC Interface Bridge (rev 01)
    00:1f.1 IDE interface: Intel Corporation 82801G (ICH7 Family) IDE Controller (rev 01)
    02:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5788 Gigabit Ethernet (rev 03)
    02:09.0 CardBus bridge: Texas Instruments PCIxx12 Cardbus Controller
    02:09.1 FireWire (IEEE 1394): Texas Instruments PCIxx12 OHCI Compliant IEEE 1394 Host Controller
    02:09.4 Communication controller: Texas Instruments PCIxx12 GemCore based SmartCard controller
    08:00.0 Network controller: Intel Corporation PRO/Wireless 3945ABG [Golan] Net
    

    My /etc/network/interfaces looks like this:

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

    And I get no output from sudo ifconfig eth0 up.

    Output from nm-applet:

    ** (nm-applet:1824): DEBUG: old state indicates that this was not a disconnect 0
    ** (nm-applet:1824): DEBUG: old state indicates that this was not a disconnect 0
    

    On second run of nm-applet:

    ** (nm-applet:2752): DEBUG: old state indicates that this was not a disconnect 0
    ** (nm-applet:2752): DEBUG: old state indicates that this was not a disconnect 0
    
    ** (nm-applet:2752): WARNING **: _nm_object_get_property: Error getting 'WpaFlags' for /org/freedesktop/NetworkManager/AccessPoint/10: (19) Method "Get" with signature "ss" on interface "org.freedesktop.DBus.Properties" doesn't exist
    
    
    
    ** (nm-applet:2752): WARNING **: _nm_object_get_property: Error getting 'RsnFlags' for /org/freedesktop/NetworkManager/AccessPoint/10: (19) Method "Get" with signature "ss" on interface "org.freedesktop.DBus.Properties" doesn't exist
    
    
    
    ** (nm-applet:2752): WARNING **: Error in getting active connection 'Vpn' property: (19) Method "Get" with signature "ss" on interface "org.freedesktop.DBus.Properties" doesn't exist
    
    
    ** (nm-applet:2752): WARNING **: _nm_object_array_demarshal: couldn't create object for /org/freedesktop/NetworkManager/ActiveConnection/0
    ** Message: <info>  No keyring secrets found for Auto HeyJude88/802-11-wireless-security; asking user.
    
    
    ** (nm-applet:2752): WARNING **: applet.c.2882 (applet_settings_new_secrets_requested_cb): couldn't find details for connection
    ** Message: <info>  No keyring secrets found for Auto HeyJude88/802-11-wireless-security; asking user.
    
    ** (nm-applet:2752): DEBUG: going for offline with icon: notification-network-wireless-disconnected
    ** (nm-applet:2752): DEBUG: foo_client_state_changed_cb
    ** (nm-applet:2752): DEBUG: foo_client_state_changed_cb
    ** (nm-applet:2752): DEBUG: foo_client_state_changed_cb
    ** (nm-applet:2752): DEBUG: going for offline with icon: notification-network-wireless-disconnected
    ** (nm-applet:2752): DEBUG: foo_client_state_changed_cb
    

    Here's more to ifconfig:

    wlan0     Link encap:Ethernet  HWaddr 00:18:de:31:70:20  
              inet addr:172.16.6.210  Bcast:172.16.6.255  Mask:255.255.255.0
              inet6 addr: fe80::218:deff:fe31:7020/64 Scope:Link
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:2384 errors:0 dropped:0 overruns:0 frame:0
              TX packets:1367 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000 
              RX bytes:514654 (514.6 KB)  TX bytes:215138 (215.1 KB)
    
    • Allan
      Allan about 12 years
      Can you run this command killall -9 nm-applet followed by nohup nm-applet & this should create a file called nohup.out in your home folder can you add the contents if any to your question
    • tekknolagi
      tekknolagi about 12 years
      Is nm network manager? What will this be doing?
    • tekknolagi
      tekknolagi about 12 years
      see my edit for details
    • Allan
      Allan about 12 years
      the commands will stop and restart network manager applet when you do this it will search for available connections and output messages to the nohup.out file.
    • tekknolagi
      tekknolagi about 12 years
      Just posted the output. That's all there is. 1824 is the pid.
    • tekknolagi
      tekknolagi about 12 years
      ran it a second time, more output
    • ivotron
      ivotron over 10 years
      for the record, in my case, the eth0 entry in the /etc/network/interfaces appears because I had installed ubuntu-server on my machine and then installed ubuntu-desktop and thus the network manager can't "see" the interface
  • tekknolagi
    tekknolagi about 12 years
    see my edit for details
  • tekknolagi
    tekknolagi about 12 years
    I still get Wired Networks \n disconnected in the menu tray
  • tekknolagi
    tekknolagi about 12 years
    added some more output from ifconfig, hope it's useful
  • Sudipta Chatterjee
    Sudipta Chatterjee about 12 years
    Right click on the network manager icon and see if "Enable networking" icon is enabled
  • tekknolagi
    tekknolagi about 12 years
    Enabled... Wireless works.
  • Admin
    Admin almost 12 years
    This works for me, but the problem reappears whenever I shutdown while connected to a wireless network, then start back up without being connected to a network. I'm not able to connect to any Wi-Fi hot-spots until I perform these steps.