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Thread: Ethernet connection not recognised.

  1. #11
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    Re: Ethernet connection not recognised.

    Hi

    I would post your log files to try to get to the root of the problem.

    Code:
    sudo apt-get install pastebinit
    Code:
    pastebinit /var/log/syslog
    Post back the URL produced.

    KInd regards
    If you believe everything you read, you better not read. ~ Japanese Proverb

    If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed. - Mark Twain

  2. #12
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    Re: Ethernet connection not recognised.

    Hi

    From the syslog file you PM'ed to me...

    This is when you first boot up.

    Code:
    May  7 16:48:05 shack NetworkManager[1906]: nm_netlink_monitor_get_flags_sync: assertion `self != NULL' failed
    May  7 16:48:05 shack NetworkManager[1906]: <warn> (eth0): couldn't get carrier state: (-1) unknown 
    May  7 16:48:05 shack NetworkManager[1906]: <info> (eth0): carrier now OFF (device state 20, deferring action for 4 seconds) 
    May  7 16:48:05 shack NetworkManager[1906]: <info> (eth0): preparing device. May  7 16:48:05 shack NetworkManager[1906]: <info> (eth0): deactivating device (reason 'managed') [2]
    ... and this is after you kill network manager and it gets respawned.

    Code:
    May  7 16:48:57 shack NetworkManager[1943]: <warn> failed to allocate link cache: (-10) Operation not supported 
    May  7 16:48:57 shack NetworkManager[1943]: <info> (eth0): carrier is ON 
    May  7 16:48:57 shack NetworkManager[1943]: <info> (eth0): new Ethernet device (driver: 'sundance' ifindex: 2) 
    May  7 16:48:57 shack NetworkManager[1943]: <info> (eth0): exported as /org/freedesktop/NetworkManager/Devices/0 
    May  7 16:48:57 shack NetworkManager[1943]: <info> (eth0): now managed
    It looks like network manager cannot get the carrier signal until you respawn. i.e it does not think it's connected to anything via the Ethernet port.

    This may be due to the error in the first line: assertion `self != NULL' failed.

    This may require some research as it's not an error i have come across before.

    EDIT:

    Can you try something ? Boot into Ubuntu but don't kill network manager. Instead unplug and replug your Ethernet cable.

    Does that get you connected ?

    Kind regards
    Last edited by matt_symes; May 7th, 2013 at 08:30 PM.
    If you believe everything you read, you better not read. ~ Japanese Proverb

    If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed. - Mark Twain

  3. #13
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    Re: Ethernet connection not recognised.

    Thanks Matt.
    Disconnecting and then re-connecting the network cable after booting up makes no difference.
    I have now re-booted both with and without the network cably plugged in, and then plugged in the cable but again no connectivity.
    The only way I can activate the Network manager is by the command: sudo pkill -9 NetworkManager
    Once connected, if I then disconnect the cable I get the error message saying I'm now offline.
    Then if I re-connect the cable it comes back up immediately.
    Hope this helps.
    Thanks and regards,
    Roger

  4. #14
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    Re: Ethernet connection not recognised.

    Hi

    My research led me here.

    https://bugzilla.redhat.com/show_bug.cgi?id=816719

    and then consequently here

    http://ubuntuforums.org/showthread.php?t=1981329

    which then linked back into the Redhat bug

    It seems your driver/card may not support carrier detection and that would explain the syslog messages.

    AnnMatt's solution (post #4) was to set up a fixed network connection by ensuring that interface is not managed by Network Manager. It's a tutorial from liberiangeek. I've looked at it and it looks fine for 12.04. You'll also need to set up DNS as also highlighted in that post.

    That sound like the kind of workaround i would apply so you may want to give that a go.

    If you need help then post back.

    I assume this is a desktop PC ?

    I'll double check on your driver and i'll also see if there's an updated Network Manager that fixes the issue.

    Kind regards
    Last edited by matt_symes; May 8th, 2013 at 01:41 PM.
    If you believe everything you read, you better not read. ~ Japanese Proverb

    If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed. - Mark Twain

  5. #15
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    Re: Ethernet connection not recognised.

    Thanks Matt,
    The possible fix you example all appears to be very nebulous and perhaps better done by an expert rather than by a ham-fisted enthusiast like me.
    I've looked for an update to Network Manager without success and searched other instances of similar problems with NM, and even tried the more simpler suggestions, but none of them appear to work - possibly because they're not quite my problem. Even modifying /etc/network/interfaces to a default ethernet didn't make any difference.
    Below is the NM status both immediately post bootup, and then after restarting it. The only difference being the state.
    I think its a timing issue in the bootup process - software/hardware.
    Any further thoughts please?
    Kind regards,
    Roger

    roj@shack:~$ nmcli -f all -p nm status
    ================================================== ================================================== ===========
    NetworkManager status
    ================================================== ================================================== ===========
    RUNNING VERSION STATE NET-ENABLED WIFI-HARDWARE WIFI WWAN-HARDWARE WWAN
    ---------------------------------------------------------------------------------------------------------------
    running 0.9.4.0 disconnected enabled enabled enabled enabled disabled
    roj@shack:~$ sudo NetworkManager
    [sudo] password for roj:
    NetworkManager is already running (pid 750)
    roj@shack:~$ sudo pkill -9 NetworkManager
    roj@shack:~$ nmcli -f all -p nm status
    ================================================== ================================================== ===========
    NetworkManager status
    ================================================== ================================================== ===========
    RUNNING VERSION STATE NET-ENABLED WIFI-HARDWARE WIFI WWAN-HARDWARE WWAN
    ---------------------------------------------------------------------------------------------------------------
    running 0.9.4.0 connected enabled enabled enabled enabled disabled
    roj@shack:~$ NetworkManager --version
    0.9.4.0
    roj@shack:~$ sudo apt-get install NetworkManager
    Reading package lists... Done
    Building dependency tree
    Reading state information... Done
    E: Unable to locate package NetworkManager
    roj@shack:~$

  6. #16
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    Re: Ethernet connection not recognised.

    Hi

    To see if Linux thinks it has an Ethernet connection at startup, run this command before restarting network manager.

    Code:
    find /sys -name carrier -exec cat {} \; -exec echo {} \; 2> /dev/null
    It could be a timing issue. Maybe network manager is querying the card/driver before it's ready ? That is just supposition though.

    We can make network manager start a bit later.

    From the terminal...

    Code:
    sudo nano /etc/init/network-manager.conf
    Look for the line that says

    Code:
    exec NetworkManager
    and on the line before it add

    Code:
    sleep 60
    Ctrl + o to save and Ctrl + x to edit.

    It'll start up 60 seconds later. If this fixes the issue then it can be adjusted downwards later.

    Kind regards
    If you believe everything you read, you better not read. ~ Japanese Proverb

    If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed. - Mark Twain

  7. #17
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    Re: Ethernet connection not recognised.

    Hi Matt,
    Adding the sleep 60 line made no difference. It just delayed the message saying no network connection by 60 secs.
    So I've removed it.
    This is the output of:
    roj@shack:~$ find /sys -name carrier -exec cat {} \; -exec echo {} \; 2> /dev/null
    1
    /sys/devices/virtual/net/lo/carrier
    1
    /sys/devices/pci0000:00/0000:00:1e.0/0000:02:01.0/net/eth0/carrier
    roj@shack:~$
    Thanks and kind regards,
    Roger

  8. #18
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    Re: [UNSOLVED] Ethernet connection not recognised.

    Hi Again Matt,
    It would appear that my version of Network Manager (0.9.4.0-0ubuntu4, 0.9.4.0-0ubuntu4.1) is causing lots of problems and many are apparently reverting to version Oubuntu3.
    This link explains more:
    http://ubuntuforums.org/showthread.p...0#post12016190
    Do you think this could be causing my problems and should I attempt to revert and install Oubuntu3?
    Unless, of course, you have meanwhile come across an alternative fix?
    Kind regards,
    Roger

  9. #19
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    Re: Ethernet connection not recognised.

    Hi

    Well judging by that output, you have a carrier signal at the start so that is not the problem.

    I would still suggest going down the route of stopping network manager managing the eth0 interface and setting it to get an IP address using DHCP in network interfaces.

    I still believe that is your best bet and simpliest fix.

    As for downgrading network manager, you look to be getting a different set of error messages than the other posters in that thread.

    However, that being said, you could certainly try it and see how it goes as it may well be a bug in network manager/netlink.

    Kind regards
    If you believe everything you read, you better not read. ~ Japanese Proverb

    If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed. - Mark Twain

  10. #20
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    16

    Re: Ethernet connection not recognised.

    Regrettably, Matt, I have tried this workaround by applying the changes for a fixed IP address, etc, as per the links you referred to but without success.
    Post changes, the bootup displayed a message 'Waiting for Network Configuration' under the startup Ubuntu logo screen, and would take all of a minute to present the desktop.
    Then the network connection symbol would be shown on the top toolbar (Eureka) but alas no internet connection when using the browser or email.
    The workaround showed both network and gateway addresses as 192.168.0.1 and I tried different settings for these, but again without success.
    As for downgrading Network Manager to the previous version, I've read up further on this and I've reached the same conclusion as yourself, that those are somewhat different - and it looks to be a complicated solution to try.
    Surely, if there is a bug in this latest version of Network Manager, then would not Ubuntu have issued a fix by now?
    Any further thoughts, please?
    And without wishing to appear disrespectful or thankless to you (far from it), how can the [SOLVED] prefix to the title of this thread be removed, in case others may have come across similar, if not the same, problems and are put-off responding, thinking it is solved?
    Kind regards,
    Roger

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